Brake system and vehicle

ABSTRACT

A brake system includes a brake activator which reduces, when a slipping condition of a right front wheel is detected based on a signal which is detected by a right detector, both braking forces on the right front wheel and a left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of an input member and which reduces, when a slipping condition of the left front wheel is detected based on a signal which is detected by a left detector, both braking forces on the left front wheel and the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member.

BACKGROUND OF THE INVENTION

1. Field of the present invention

The present invention relates to a brake system for a vehicle including a body frame that leans, two front wheels, and one rear wheel and a vehicle including the brake system.

2. Description of the Related Art

A vehicle is known which includes a body frame which leans in a left-and-right direction of the vehicle when the vehicle is cornering, two front wheels aligned side by side in a left-and-right direction of the body frame, and a central rear wheel which is disposed centrally between the two front wheels when the vehicle is seen from the front thereof with the body frame being in an upright state (for example, refer to International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio). A vehicle is also known which includes a body frame which leans in a left-and-right direction of the vehicle when the vehicle is cornering, two front wheels aligned side by side in a left-and-right direction of the body frame, and two rear wheels (for example, refer to Japanese Patent Unexamined Publication JPA-2011-195099).

The vehicles described in International Patent Publication No. 2012/007819, Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio and Japanese Patent Unexamined Publication JP-A-2011-195099 are vehicles which include a body frame which leans and two front wheels. The vehicle including the body frame which leans and the two front wheels includes a link mechanism. The link mechanism includes an upper cross member and a lower cross member. The link mechanism also includes a right side rod which supports right end portions of the upper cross member and the lower cross member and a left side rod which supports left end portions of the upper cross member and the lower cross member.

A middle portion of the upper cross member is connected to the body frame via a middle upper bearing so as to turn about a middle upper axis which extends in a front-and-rear direction of the body frame. The middle upper axis is inclined in such a way as to extend forwards in the front-and-rear direction of the body frame and upwards in an up-and-down direction of the body frame. The right end portion of the upper cross member is connected to the right side rod via a right upper bearing so as to turn about a right upper axis which extends in the front-and-rear direction of the body frame. The left end portion of the upper cross member is connected to the left side rod via a left upper bearing so as to turn about a left upper axis which extends in the front-and-rear direction of the body frame. A middle portion of the lower cross member is connected to the body frame via a middle lower bearing so as to turn about a middle lower axis which extends in the front-and-rear direction of the body frame. As with the middle upper axis, the middle lower axis is also inclined in such a way as to extend forwards in the front-and-rear direction of the body frame and upwards in the up-and-down direction of the body frame. The right end portion of the lower cross member is connected to the right side rod via a right lower bearing so as to turn about a right lower axis which extends in the front-and-rear direction of the body frame. The left end portion of the lower cross member is connected to the left side rod via a left lower bearing so as to turn about a left lower axis which extends in the front-and-rear direction of the body frame.

When the body frame leans in the left-and-right direction of the vehicle from its upright state, the upper cross member and the lower cross member turn relative to the body frame about the middle upper axis and the middle lower axis, respectively, so that a relative position of the two front wheels in relation to the up-and-down direction of the body frame changes. In addition, the middle upper axis and the middle lower axis are inclined in such a way as to extend forwards in the front-and-rear direction of the body frame and upwards in the up-and-down direction of the body frame, and therefore, the two front wheels move farther rearwards as they move upwards, while the two front wheels are displaced farther forwards as they move downwards. With the body frame being in the upright state, the upper cross member and the lower cross member are above the two front wheels in the up-and-down direction of the body frame. The link mechanism is above the left front wheel and the right front wheel in the up-and-down direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in an upright state.

The vehicle including the body frame which leans and the two front wheels includes a right shock absorbing device which supports the right front wheel so as to move in the up-and-down direction of the body frame and a left shock absorbing device which supports the left front wheel so as to move in the up-and-down direction of the body frame. The right shock absorbing device is supported by the right side rod so that the right shock absorbing device is able to turn about a right axis which extends in the up-and-down direction of the body frame. The left shock absorbing device is supported by the left side rod so that the left shock absorbing device is able to turn about a left axis which extends in the up-and-down direction of the body frame. The vehicle described in International Patent Publication No. 2012/007819 includes further a handlebar, a steering shaft and a turn transmission. The handlebar is fixed to the steering shaft. The steering shaft is supported so as to turn relative to the body frame. When the handlebar is turned, the steering shaft also turns. The turn transmission transmits a turning motion of the steering shaft to the right shock absorbing device and the left shock absorbing device.

The vehicle including the body frame which leans and the two front wheels includes many on-board components provided on the periphery of the steering shaft. The on-board components include a lamp such as a headlamp, a radiator, a reservoir tank, an electric component such as a horn, a main switch of the vehicle, a stowage box, a stowage pocket and the like.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio include a left and right front wheel braking input member which controls a braking force generated on the right front wheel and the left front wheel. Additionally, the vehicle includes a rear wheel braking input member which controls a braking force generated in the central rear wheel. Further, the vehicle includes left and right front wheel and central rear wheel braking input member which controls braking forces generated in the central rear wheel and the right front and left front wheels.

A front wheel master cylinder is activated when the left and right front wheels braking input member is operated. A hydraulic pressure generated by the front wheel master cylinder activates a primary tandem master cylinder. A hydraulic pressure generated in the primary tandem master cylinder is divided evenly to be transmitted to a right brake provided on the right front wheel and a left brake provided on the left front wheel. The right brake and the left brake which have received the hydraulic pressures generate braking forces.

A rear wheel master cylinder is activated when the rear wheel braking input member is operated. A hydraulic pressure generated by the rear wheel master cylinder activates a secondary master cylinder. A hydraulic pressure generated by the secondary master cylinder is transmitted to a central rear brake provided on the central rear wheel. The central rear brake which has received the hydraulic pressure generates braking forces.

A front and rear wheel master cylinder is activated when the left and right front wheels and rear wheel input member is operated. A hydraulic pressure generated by the front and rear wheels master cylinder activates the secondary master cylinder. A hydraulic pressure generated by the secondary master cylinder is transmitted to a central rear brake provided on the central rear wheel. Additionally, a portion of the hydraulic pressure generated by the front and rear wheel master cylinder passes through the secondary master cylinder to activate the primary tandem master cylinder. A hydraulic pressure generated by the primary tandem master cylinder is divided evenly to be transmitted to the right brake provided on the right front wheel and the left brake provided on the left front wheel. The central rear brake, the right brake, and the left brake which have received the hydraulic pressures generate braking forces.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio use the three types of brake systems which are different in operation.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio which include the body frame which leans, the two front wheels, and the single rear wheel include the right front wheel, the central rear wheel, and the left front wheel which are aligned side by side in the left-and-right direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in an upright state. Because of this, when the vehicle runs, the right front wheel, the central rear wheel, and the left front wheel basically pass over different road surfaces. The vehicle described in Japanese Patent Unexamined Publication JPA-2011-195099 which includes the body frame which leans, the two front wheels, and the two rear wheels include the right front wheel, the right rear wheel, the left front wheel, and the left rear wheel which are aligned side by side in the left-and-right direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in an upright state. Because of this, when the vehicle runs, the right front wheel and the right rear wheel pass over road surfaces which are almost the same, and the left front wheel and the left rear wheel pass over road surfaces which are almost the same. In this way, the road surfaces which the wheels of the vehicle pass over which includes the body frame which leans, the two front wheels, and the single central rear wheel are different from the road surfaces which the wheels of the vehicle which includes the body frame which leans, the two front wheels, and the two rear wheels.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio which include the body frame which leans, the two front wheels, and the single rear wheel include the two front wheels, the two shock absorbing devices which support individually the two front wheels, the link mechanism which supports the two shock absorbing devices, the single central rear wheel, and one shock absorbing device which supports the single central rear wheel. The vehicle described in Japanese Patent Unexamined Publication JP-A-2011-195099 which includes the body frame which leans, the two front wheels, and the two rear wheels include the two front wheels, two shock absorbing devices which support individually the two front wheels, a link mechanism which supports the two shock absorbing devices, the two rear wheels, and one shock absorbing device which supports the two rear wheels.

There is a tendency that a ratio of the magnitude of load applied to the front wheels to the magnitude of load applied to the front wheels and the rear wheel or wheels becomes larger relative to that in the vehicle including the body frame which leans, the two front wheels, and the single central rear wheel than in the vehicle including the body frame which leans, the two front wheels, and the two rear wheels. It is noted that the load applied to the front wheels is not necessarily larger than the load applied to the rear wheel or wheels. In fact, the loads applied individually to the front wheels and the rear wheel or wheels change depending upon the layout of the drive source such as the engine mounted on the body frame, the seated position of the rider or the like.

The vehicles described in International Patent Publication No. 2012/007819, Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio and Japanese Patent Unexamined Publication JP-A-2011-195099 which include the body frame which leans and the two front wheels turn with the body frame leaning in the left-and-right direction of the vehicle. As this occurs, the vehicle including the body frame which leans and the two front wheels has a tendency that a load applied to the front wheel which defines the inner wheel having a smaller turning radius becomes relatively larger than a load applied to the front wheel which defines the outer wheel having a larger turning radius. This is attributed to the configuration of the vehicle in which the middle upper axis and the middle lower axis are provided so as to lean in such a way as to extend forwards in the front-and-rear direction of the body frame and upwards in the up-and-down direction of the body frame. With the body frame leaning in the left-and-right direction of the vehicle, the inner wheel is positioned upwards and the outer wheel is positioned downwards in the up-and-down direction of the body frame. In addition, the inner wheel is positioned rearwards in the front-and-rear direction and the outer wheel is positioned forwards in the front-and-rear direction of the body frame. A distance between the front wheel which defines the inner wheel and the rear wheel is shorter than a distance between the front wheel which defines the outer wheel and the rear wheel. Due to this, the vehicle including the body frame which leans and the two front wheels has the tendency that the load applied to the front wheel which defines the inner wheel having the smaller turning radius becomes relatively larger than the load applied to the front wheel which defines the outer wheel having the larger turning radius.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio which include the body frame which leans, the two front wheels, and the single rear wheel include the link mechanism which is provided above the right front wheel and the left front wheel in the up-and-down direction of the body frame when the vehicle is viewed from the front with the body frame being in an upright state. In this configuration, with the body frame being in the upright state, the right front wheel, the right shock absorbing device, the left shock absorbing device, and the left front wheel are aligned side by side in the left-and-right direction of the body frame, and the link mechanism is not present between the right front wheel and the left front wheel. Because of this, the distance between the right front wheel and the left front wheel of the vehicle described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio which include the body frame which leans, the two front wheels, and the single rear wheel is shorter than a distance between a right front wheel and a left front wheel of a vehicle in which a link mechanism is disposed between the right front wheel and the left front wheel. This causes a tendency that a difference between a load applied to the front wheel which defines an outer wheel having a larger turning radius and a load applied to the front wheel which defines an inner wheel having a smaller turning radius becomes smaller in the vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio which include the body frame which leans, the two front wheels, and the single rear wheel than that in the vehicle in which the link mechanism is disposed between the right front wheel and the left front wheel.

The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio have the configuration and characteristics which are described above. The vehicles described in International Patent Publication No. 2012/007819 and Catalogo partidi ricambio, MP3 300 LT Mod. ZAPM64102, Piaggio use the three types of brake systems which are different in operation.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a brake system for a vehicle including a body frame which leans, two front wheels, and a single rear wheel and which operates differently from the three types of brake systems which are conventional. Other preferred embodiments of the present invention provide a vehicle including a brake system which operates differently from the three types of brake systems which are conventional, a body frame which leans, two front wheels, and a single rear wheel.

A preferred embodiment of the present invention includes the following configuration.

(1) A brake system for a vehicle including a body frame; a right front wheel and a left front wheel which are aligned in a left-and-right direction of the body frame when the vehicle is viewed from a front thereof with the body frame being in an upright state; a central rear wheel which is provided behind the right front wheel and the left front wheel in the front-and-rear direction of the body frame and disposed between the right front wheel and the left front wheel when the vehicle is viewed from the front thereof with the body frame being in the upright state; a right shock absorbing device which supports the right front wheel at a lower portion thereof and absorbs an upward displacement of the right front wheel in an up-and-down direction of the body frame; a left shock absorbing device which supports the left front wheel at a lower portion thereof and absorbs an upward displacement of the left front wheel in the up-and-down direction of the body frame; and a link mechanism which is provided above the right front wheel and the left front wheel in the up-and-down direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in the upright state and supports an upper portion of the right shock absorbing device and an upper portion of the left shock absorbing device so as to turn, at least a portion of which is supported on the body frame so as to turn about a turning axis which extends forwards in the front-and-rear direction of the body frame and upwards in the up-and-down direction of the body frame, the brake system including a right front brake which is provided on the right front wheel and which generates a braking force on the right front wheel; a left front brake which is provided on the left front wheel and which generates a braking force on the left front wheel; an input member which is able to be operated to turn by a rider; a right front wheel slip detector that detects a slipping condition of the right front wheel; a left front wheel slip detector that detects a slipping condition of the left front wheel; and a brake activator that, at least while the vehicle is turning with the body frame leaning in a left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation as a result of operation of the input member, when a slipping condition of the right front wheel is detected based on a signal detected by the right front wheel slip detector, to reduce a braking force on the right front wheel and a braking force on the left front wheel to a lower level than a level of a braking force which is obtained by operating the input member by controlling both an operating condition of the right front brake on the right front wheel and an operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector, and when a slipping condition of the left front wheel is detected based on a signal detected by the left front wheel slip detector, to reduce a braking force on the left front wheel and a braking force on the right front wheel to a lower level than a level of a braking force which is obtained by operating the input member by controlling both an operating condition of the left front brake on the left front wheel and an operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector.

According to the configuration (1) above, the brake system includes the right front brake, the left front brake, the input, and the brake activator which activates the right front brake and the left front brake by operating the input. Because of this, the brake system is able to be used for a vehicle which includes a body frame which leans, two front wheels, and one rear wheel.

The vehicle including the body frame which leans, the two front wheels, and the single rear wheel exhibits the following characteristics while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle.

When the vehicle is turning with the body frame leaning to the right of the vehicle, the right front wheel defines an inner wheel having a smaller turning radius, and the left front wheel defines an outer wheel having a larger turning radius. When the vehicle is turning with the body frame leaning to the left of the vehicle, the left front wheel defines the inner wheel having the smaller turning radius, and the right left front wheel defines the outer wheel having the larger turning radius. Since the vehicle is turning while causing the body frame to lean in the left-and-right direction of the vehicle by the link mechanism at least a portion of which is supported on the body frame so as to turn about the turning axis which extends forwards in the front-and-rear direction of the body frame and upwards in the up-to-right direction of the body frame, the vehicle has a tendency that a load applied to the front wheel which defines the inner wheel becomes larger basically than a load which is applied to the front wheel which defines the outer wheel of the vehicle which is turning. Moreover, the vehicle including the single central rear wheel has a tendency that a load applied to the front wheels becomes larger relatively than a load applied to the rear wheel, compared with a vehicle including a left rear wheel and a right rear wheel. There is a tendency that the load applied to the front wheel which defines the inner wheel becomes larger basically than the load applied to the front wheel which defines the outer wheel of the vehicle which is turning. In addition, the front wheel which defines the inner wheel and the front wheel which defines the outer wheel of the vehicle which is turning pass over on different road surfaces. Because of this, there is a possibility that the two front wheels pass over road surfaces having different friction coefficients.

The inventor of the present invention has studied brake systems while taking into consideration the characteristics of the vehicle having the body frame which leans, the two front wheels, and the single rear wheel. Additionally, the inventor has studied the braking forces on the right front wheel and the left front wheel at least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation. As a result of the studies, it has been discovered that when a slipping condition of the front wheel which defines the inner wheel is not detected but a slipping condition of the front wheel which defines the outer wheel is detected based on signals detected by the right front wheel slip detector and the left front wheel slip detector, in case the braking force on the front wheel which defines the outer wheel is reduced to a lower level than a level of a braking force which is obtained by operating the input member by controlling the operating condition of the front brake of the front wheel which defines the outer wheel which is in the slipping condition, a difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large. When the difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large and the braking force on the front wheel which defines the inner wheel becomes larger than the braking force on the front wheel which defines the outer wheel, a force is applied to the body frame which acts in a direction in which the leaning angle of the body frame from the vertical direction is reduced. In addition, when the difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large and the braking force on the front wheel which defines the inner wheel becomes smaller than the braking force on the front wheel which defines the outer wheel, a force is applied to the body frame which acts in a direction in which the leaning angle of the body frame from the vertical direction is increased.

The inventor of preferred embodiments of the present invention has conceived a brake system which takes this condition into consideration.

When referred to herein, slip refers to a slip in a rotating direction of the right front wheel, a slip in a rotating direction of the left front wheel, and a slip in a rotating direction of the rear wheel. For example, this slip is able to be detected based on a difference between a body speed and a wheel speed. Further, when one of the three wheels is in a slipping condition, this means that the wheel in question is likely to lock.

According to the configuration (1) above, at least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation as a result of operation of the input member, when a slipping condition of the right front wheel is detected based on a signal detected by the right front wheel slip detector, the brake activator reduces the braking force on the right front wheel and the braking force on the left front wheel to the lower level than the level of the braking force which is obtained by operating the input member by controlling both the operating condition of the right front brake on the right front wheel and the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector. At least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation as a result of operation of the input member, when a slipping condition of the left front wheel is detected based on a signal detected by the left front wheel slip detector, the brake activator reduces the braking force on the left front wheel and the braking force on the right front wheel to the lower level than the level of the braking force which is obtained by operating the input member by controlling both the operating condition of the left front brake on the left front wheel and the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector. While the vehicle is turning with the body frame leaning and both the right front brake and the left front brake are in operation, the braking forces in both the right front wheel and the left front wheel are reduced to the lower level than the level of the braking force which is obtained as a result of the operation of the input member by controlling the operating conditions of both the right front brake and the left front brake based on the detection signal of one of the right front wheel slip detector and the left front wheel slip detector. Because of this, it is possible to provide the brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(2) The brake system, wherein the brake activator reduces a braking force on the left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to a physical quantity in relation to a braking force on the right front wheel based on a signal detected by the right front wheel slip detector and reduces a braking force on the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel according to a physical quantity in relation to a braking force on the left front wheel based on a signal detected by the left front wheel slip detector.

According to the configuration (2) above, the brake activator reduces the braking force on the left front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to the physical quantity in relation to the braking force on the right front wheel based on the signal detected by the right front wheel slip detector. In addition, the brake activator reduces the braking force on the right front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel according to the physical quantity in relation to the braking force on the left front wheel based on the signal detected by the left front wheel slip detector. The signals detected by the slip detectors are not processed directly but are controlled indirectly according to the physical quantities in relation to the braking forces of the front wheels which are the indirect physical quantities based on the signals detected by the slip detectors. Because of this, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(3) The brake system, wherein the brake activator reduces a braking force on the left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to a physical quantity in relation to an operating condition of the right front brake based on a signal detected by the right front wheel slip detector and reduces a braking force on the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling an operating condition of the right front brake on the right front wheel according to a physical quantity in relation to an operating condition of the left front brake based on a signal detected by the left front wheel slip detector.

According to the configuration (3) above, the brake activator reduces the braking force on the left front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to the physical quantity in relation to the operating condition of the right front brake based on the signal detected by the right front wheel slip detector. In addition, the brake activator reduces the braking force on the right front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel according to the physical quantity in relation to the operating condition of the left front brake based on the signal detected by the left front wheel slip detector. The signals detected by the slip detectors are not processed directly but are controlled according to the physical quantities in relation to the operating condition of the front brake which are the indirect physical quantities based on the signals detected by the slip detectors. Because of this, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(4) The brake system, wherein the brake activator reduces a braking force on the left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to a control quantity which controls an operating condition of the right front brake based on a signal detected by the right front wheel slip detector and reduces a braking force on the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling an operating condition of the right front brake on the right front wheel according to a control quantity which controls an operating condition of the left front brake based on a signal detected by the left front wheel slip detector.

According to the configuration (4) above, the brake activator reduces the braking force on the left front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel according to the control quantity which controls the operating condition of the right front brake based on the signal detected by the right front wheel slip detector. In addition, the brake activator reduces the braking force on the right front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel according to the control quantity which controls the operating condition of the left front brake based on the signal detected by the left front wheel slip detector. The signals detected by the slip detectors are not processed directly but are processed according to the control quantities which are indirect electric signals based on the signals detected by the slip detectors and by which the operating conditions of the front brake are controlled. Because of this, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(5) The brake system, wherein when a slipping condition of the right front wheel is detected based on a signal detected by the right front wheel slip detector, the brake activator firstly reduces a braking force on the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel and thereafter reduces a braking force on the left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector, and when a slipping condition of the left front wheel is detected based on a signal detected by the left front wheel slip detector, the brake activator firstly reduces a braking force on the left front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel and thereafter reduces a braking force on the right front wheel to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector.

According to the configuration (5) above, when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector, the brake activator firstly reduces the braking force on the right front wheel to the lower level than the level of the braking force which is obtained by operation of the input member by controlling the operating condition of the right front brake on the right front wheel and thereafter reduces the braking force on the left front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector. In addition, when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector, the brake activator firstly reduces the braking force on the left front wheel to the lower level than the level of the braking force which is obtained by operation of the input member by controlling the operating condition of the left front brake on the left front wheel and thereafter reduces the braking force on the right front wheel to the lower level than the level of the braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector. While the vehicle is turning with the body frame leaning and both the right front brake and the left front brake are in operation, the braking force on the right front wheel and the braking force on the left front wheel are reduced to the lower level than the level of the braking force which is obtained as a result of operation of the input member with the certain time lag by controlling the operating conditions of both the right front brake and the left front brake based on the detection signal of one of the right front wheel slip detector and the left front wheel slipping condition detector. Because of this, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(6) The brake system, wherein when a slipping condition of the right front wheel is detected based on a signal detected by the right front wheel slip detector, the brake activator reduces a braking force on the right front wheel and a braking force on the left front wheel at the same time to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the right front brake on the right front wheel and controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector, and when a slipping condition of the left front wheel is detected based on a signal detected by the left front wheel slip detector, the brake activator reduces a braking force on the right front wheel and a braking force on the left front wheel at the same time to a lower level than a level of a braking force which is obtained as a result of operation of the input member by controlling the operating condition of the left front brake on the left front wheel and controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector.

According to the configuration (6) above, when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector, the brake activator reduces the braking force on the right front wheel and the braking force on the left front wheel at the same time to the lower level than the level of the braking force which is obtained as a result of the operation of the input member by controlling the operating condition of the right front brake on the right front wheel and controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector. In addition, when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector, the brake activator reduces the braking force on the right front wheel and the braking force on the left front wheel at the same time to the lower level than the level of the braking force which is obtained as a result of the operation of the input member by controlling the operating condition of the left front brake on the left front wheel and controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector. While the vehicle is turning with the body frame leaning and both the right front brake and the left front brake are in operation, the braking force on the right front wheel and the braking force on the left front wheel are reduced to the lower level than the level of the braking force which is obtained as a result of the operation of the input member at the same time by controlling the operating conditions of both the right front brake and the left front brake based on the detection signal of one of the right front wheel slip detector and the left front wheel slipping condition detector. Because of this, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(7) A vehicle including the brake system according to any one of the preferred embodiments of the present invention above.

According to the configuration (7) above, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(8) The vehicle, wherein the right shock absorbing device includes a right telescopic element that extends and contracts in an extending and contracting direction which extends in the up-and-down direction of the body frame and allows the right front wheel to be displaced in the extending and contracting direction of the right telescopic element, and the left shock absorbing device includes a left telescopic element that extends and contracts in an extending and contracting direction which extends in the up-and-down direction of the body frame and allows the left front wheel to be displaced in the extending and contracting direction of the left telescopic element.

According to the configuration (8) above, the displacement of the right front wheel and the left front wheel in the up-and-down direction of the body frame by the right shock absorbing device and the left shock absorbing device is larger than the displacement of the right front wheel and the left front wheel in the up-and-down direction of the body frame by the link-type shock absorbing devices used conventionally. Because of this, the change in posture of the vehicle becomes larger in the vehicle including the configuration (8) above than in the conventional vehicle including the link-type shock absorbing devices. The vehicle including the configuration of (8) above has a tendency that the load applied to the front wheel which defines the inner wheel becomes larger basically than the load applied to the front wheel which defines the outer wheel of the vehicle which is turning, by the change in posture of the vehicle. The brake system according to any one of the preferred embodiments of the present invention above is able to be used for a vehicle including the telescopic shock absorbing devices which allow a large displacement of the front wheels in the up-and-down direction of the body frame, the body frame which leans, the two front wheels, and the single rear wheel. According to the configuration (8) above, it is possible to provide a brake system for the vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used.

A preferred embodiment of the present invention preferably includes the following configuration.

(9) The vehicle, wherein the link mechanism is provided above the right front wheel and the left front wheel in the up-and-down direction of the body frame when the vehicle with the body frame being in the upright state is viewed from the front thereof, and the right front wheel and the left front wheel overlap the central rear wheel when the vehicle is viewed from the front thereof with the right shock absorbing device and the left shock absorbing device turned most relative to the link mechanism.

According to the configuration (9) above, the distance between the right front wheel and the left front wheel becomes short. Because of this, the difference between the turning radius of the inner wheel and the turning radius of the outer wheel becomes small. In addition, by making the difference in turning radius small, it is possible to make the difference small between the load applied to the front wheel which defines the inner wheel and the load applied to the front wheel which defines the outer wheel of the vehicle which is turning. The brake system according to any one of the preferred embodiments of the present invention above is able to be used for the vehicle including the body frame which leans, the single rear wheel and the right front wheel and the left front wheel which are disposed with a short distance therebetween. In particular, it is especially preferable to use the brake system according to configuration (6) above. According to the configuration (9) above, it is possible to provide a vehicle including the body frame which leans, the single rear wheel, the right front wheel and the left front wheel which are disposed with a short distance defined therebetween and a brake system which differs in operation from the conventional three brake systems.

A preferred embodiment of the present invention preferably includes the following configuration.

(10) The vehicle, wherein the vehicle includes a second brake system which includes a second input member which differs from the input member; and a second brake activator which starts activating the right front brake, the left front brake, and a central rear brake which is provided on the central rear wheel as a result of operation of the second input member at least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle.

According to the configuration (10) above, the vehicle includes the second brake system which includes the second input member which differs from the input member, and the second brake activator which activates the right front brake, the left front brake, and a central rear brake which is provided on the central rear wheel as a result of the operation of the second input member at least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle. Consequently, it is possible to provide a vehicle including the body frame which leans, the single rear wheel, the right front wheel and the left front wheel which are disposed with the short distance defined therebetween and two types of brake systems which differ in operation.

A preferred embodiment of the present invention preferably includes the following configuration.

(11) The vehicle, wherein the second brake activator activates the right front brake and the left front brake by using at least a portion of the brake activator.

According to the configuration (11) above, the second brake activator uses at least a portion of the brake activator, and therefore, the system configuration is simple.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall side view of a vehicle according to a first preferred embodiment of the present invention.

FIG. 2 is a front view of a front portion of the vehicle shown in FIG. 1.

FIG. 3 is a plan view of the front portion of the vehicle shown in FIG. 1.

FIG. 4 is a plan view of the front portion of the vehicle in a state where the vehicle shown in FIG. 1 is steered.

FIG. 5 is a front view of the front portion of the vehicle in a state where the vehicle shown in FIG. 1 is caused to lean.

FIG. 6 is a front view of the front portion of the vehicle in a state where the vehicle shown in FIG. 1 is steered and is caused to lean.

FIG. 7 is a side view of a left shock absorber of the vehicle shown in FIG. 1.

FIG. 8A shows diagrams showing positions of the vehicle and wheels in a front-and-rear direction as viewed from above in an up-and-down direction of a body frame.

FIG. 8B shows diagrams showing positions of the vehicle and wheels in a front-and-rear direction as viewed from above in an up-and-down direction of a body frame.

FIG. 9 is a diagram showing an example of a preferred embodiment (a first preferred embodiment of the present invention) of a brake system shown in FIGS. 8A and 8B.

FIG. 10 is a diagram showing a modified example (a second preferred embodiment of the present invention) of the brake system shown in FIGS. 8A and 8B.

FIG. 11 is a diagram showing a modified example (a third preferred embodiment of the present invention) of the brake system shown in FIGS. 8A and 8B.

FIG. 12 is a diagram showing a modified example (a fourth preferred embodiment of the present invention) of the brake system shown in FIGS. 8A and 8B.

FIG. 13 is a diagram showing a modified example (a fifth preferred embodiment of the present invention) of the brake system shown in FIGS. 8A and 8B.

FIG. 14 is a diagram showing a modified example (a sixth preferred embodiment of the present invention) of the brake system shown in FIGS. 8A and 8B.

FIG. 15 is a diagram showing an example of a preferred embodiment (a first preferred embodiment of the present invention) of a hydraulic pressure unit shown in FIGS. 8A and 8B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described based on preferred embodiments by reference to the drawings.

In the following descriptions, an arrow F in the drawings indicates a forward direction of a vehicle and an arrow B indicates a rearward direction of the vehicle. An arrow U indicates an upward direction of the vehicle and an arrow D indicates a downward direction of the vehicle. An arrow R in the drawings indicates a rightward direction of the vehicle and an arrow L indicates a leftward direction of the vehicle. The vehicle turns by causing a body frame to lean in a left-and-right direction of the vehicle relative to the vertical direction. Then, directions are also defined based on the body frame separately from the directions of the vehicle. In the drawings, an arrow FF indicates a forward direction based on the body frame, and an arrow FB indicates a rearward direction based on the body frame. In the drawings, an arrow FU indicates an upward direction based on the body frame, and an arrow FD indicates a downward direction based on the body frame. In the drawings, an arrow FR indicates a rightward direction based on the body frame, and an arrow FL indicates a leftward direction based on the body frame. In the description, the front-and-rear direction of the vehicle, the up-and-down direction of the vehicle and the left-and-right direction of the vehicle denote the front-and-rear, the left-and-right and up-and-down directions as viewed from a rider who rides on the vehicle, and those directions are based on the vehicle. Additionally, in this description, the front-and-rear direction of the body frame, the up-and-down direction of the body frame, and the left-and-right direction of the body frame denote the front-and-rear, the left-and-right and up-and-down direction as viewed from the rider who rides on the vehicle, and those directions are based on the body frame. A center in a vehicle's width direction refers to a center of a vehicle's width in the left-and-right direction of the vehicle. In other words, the center in the vehicle's width direction refers to a center of the left-and-right direction of the vehicle. Additionally, in the description, an upright state denotes a state where the up-and-down direction of the body frame coincides with the vertical direction. In this state, the direction of the vehicle coincides with the direction of the body frame. When the vehicle is turning with the body frame leaning in the left-and-right direction relative to the vertical direction, the left-and-right direction of the vehicle does not coincide with the left-and-right direction of the body frame. Additionally, the up-and-down direction of the vehicle does not coincide with the up-and-down direction of the body frame, too. However, the front-and-rear direction of the vehicle coincides with the front-and-rear direction of the body frame.

Hereinafter, referring to FIGS. 1 to 7, a vehicle according to a first preferred embodiment of the present invention will be described.

In the first preferred embodiment, a brake system will be described which is mounted on, for example, a three-wheeled vehicle (hereinafter, referred to as a vehicle) including a body frame which leans, two front wheels, and one front wheel.

FIG. 1 is an overall side view of a vehicle as viewed from the left of a left-and-right direction of a body frame.

As shown in FIG. 1, a vehicle 1001 includes a vehicle main body portion 1002. The vehicle 1001 includes a pair of left and right front wheels 1003. The vehicle 1001 includes a central rear wheel 1004. The vehicle 1001 includes a steering mechanism 1007. The vehicle 1001 includes a link mechanism 1005. The vehicle main body portion 1002 includes a body frame 1021, a body cover 1022, a seat 1024 and a power unit 1025.

The body frame 1021 includes a headstock 1211, a down frame 1212, an under frame 1214, and a rear frame 1213. In FIG. 1, in the body frame 1021, portions which are hidden by the body cover 1022 are shown by broken lines. The body frame 1021 supports the power unit 1025, the seat 1024, and the like. The body frame 1021 supports the power unit 1025, the seat 1024 and the like directly or indirectly via brackets. The power unit 1025 includes a drive source such as an engine, an electric motor or the like, a transmission and the like. In addition, the central rear wheel 1004 is supported on the power unit 1025. A driving force of the drive source is transmitted to the central rear wheel 1004 via the transmission. Further, the power unit 1025 is supported on the body frame 1021 so as to swing. A front portion of the power unit 1025 is supported on the body frame 1021 so as to swing. The power unit 1025 is supported on the body frame 1021 via a rear shock absorbing device 1025A. A rear portion of the power unit 1025 is supported on the body frame 1021 via the rear shock absorbing device 1025A. This configuration allows the central rear wheel 1004 to be displaced in an up-and-down direction of the body frame.

The headstock 1211 is disposed at a front portion of the vehicle 1001. A steering shaft 1060 of the steering mechanism 1007 is inserted into the headstock 1211 so as to be turned therein. An upper portion of the headstock 1211 is positioned farther rearwards than a lower portion thereof when the body frame is viewed from the left-and-right direction of the vehicle. The headstock 1211 is disposed so that a turning axis thereof inclines relative to the up-and-down direction of the body frame. The turning axis of the headstock 1211 extends upwards and rearwards of the body frame. The steering mechanism 1007 and the link mechanism 1005 are disposed on the circumference of the headstock 1211. The headstock 1211 supports the link mechanism 1005. The headstock 1211 supports at least a portion of the link mechanism 1005 so as to turn. The headstock 1211 supports at least a portion of the link mechanism 1005 so as to turn about a turning axis which extends forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021.

The down frame 1212 is connected to the headstock 1211. The down frame 1212 is disposed behind the headstock 1211 and extends along the up-and-down direction of the vehicle. The under frame 1214 is connected to a lower portion of the down frame 1212. The under frame 1214 extends towards the rear from the lower portion of the down frame 1212. The rear frame 1213 extends rearwards and upwards directly behind the under frame 1214. The rear frame 1213 supports the seat 1024, the power unit 1025, a tail lamp and the like.

The body frame 1021 is covered by the body cover 1022. The body cover 1022 includes a front cover 1221, pair of left and right front mudguards 1223, a leg shield 1225, a center cover 1226 and a rear mudguard 1224. The body cover 1022 is a body structure which covers at least a portion of elements such as the pair of left and right front wheels 1003, the body frame 1021, the link mechanism 1005 and the like which are mounted on the vehicle.

The front cover 1221 is positioned ahead of the seat 1024. The front cover 1221 covers at least a portion of the steering mechanism 1007 and the link mechanism 1005. The leg shield 1225 which covers at least a portion of the legs of the rider from the front is disposed behind the pair of left and right front wheels 1003 and ahead of the seat 1024. The center cover 1226 is disposed so as to cover the circumference of the rear frame 1213. The center cover 1226 is disposed so as to cover an upper portion of the rear frame 1213. The center cover 1226 is disposed so as to cover left and right side portions of the rear frame 1213.

At least portions of the pair of left and right front mudguards 1223 are disposed directly below the front cover 1221. At least portions of the pair of left and right front mudguards 1223 are disposed directly above the pair of left and right front wheels 1003, respectively. At least a portion of a rear mudguard 1224 is disposed directly above the central rear wheel 1004.

At least portions of the pair of left and right front wheels 1003 are disposed directly below the headstock 1211 in the upright state. At least portions of the pair of left and right front wheels 1003 are disposed directly below the front cover 1221 in the upright state. At least a portion of the central rear wheel 1004 is disposed directly below the center cover 1226 or the seat 1024. At least a portion of the central rear wheel 1004 is disposed directly below the rear mudguard 1224.

FIG. 2 is a front view of the front portion of the vehicle 1001 shown in FIG. 1 when viewed from the front thereof. FIG. 2 is the view resulting from viewing the vehicle 1001 from the front thereof with the body frame 1021 being in the upright state. FIG. 3 is a plan view of the front portion of the vehicle 1001 shown in FIG. 1 when viewed from above. FIG. 3 is the view resulting from viewing the vehicle 1001 from above with the body frame 1021 being in the upright state. FIGS. 2 and 3 show the front portion of the vehicle 1001 as seen through the body cover 1022.

As shown in FIGS. 2 and 3, the steering mechanism 1007 includes a steering effort transmission 1006, a left shock absorber 1033, a second shock absorber 1034 and the pair of left and right front wheels 1003.

The pair of right and left front wheels 1003 includes a left front wheel 1031 and a right front wheel 1032. The left front wheel 1031 is disposed on the left of the down frame 1212 which defines a portion of the body frame 1021 in the left-and-right direction of the body frame 1021. The right front wheel 1032 is disposed on the right of the down frame 1212 which defines a portion of the body frame 1021 in the left-and-right direction of the body frame 1021. The left front wheel 1031 and the right front wheel 1032 are aligned side by side in the left-and-right direction of the body frame 1021 when the vehicle 1001 is viewed from the front thereof with the body frame 1021 being in the upright state. Additionally, a left front mudguard 1227 is disposed directly above the left front wheel 1031. A right front mudguard 1228 is disposed directly above the right front wheel 1032. The left front wheel 1031 is supported by the left shock absorber 1033. The right front wheel 1032 is supported by the right shock absorber 1034.

The left shock absorber 1033 is preferably a so-called telescopic shock absorber and absorbs vibrations caused by the left front wheel 1031 when the left front wheel 1031 receives a load from the road surface. The left shock absorber 1033 includes a left lower portion 1033 a (a left outer element) and a left upper portion 1033 b (a left inner element). The left shock absorber 1033 includes a left side member supporting portion 1053A. The left front wheel 1031 is supported by the left lower portion 1033 a. The left lower portion 1033 a extends in the up-and-down direction of the body frame 1021, and a left wheel axle 1314 is supported at a lower end thereof. The left wheel axle 1314 supports the left front wheel 1031. The left upper portion 1033 b is disposed directly above the left lower portion 1033 a with a portion thereof inserted in the left lower portion 1033 a. The left shock absorber 1033 extends and contracts as a result of the left upper portion 1033 b moving relative to the left lower portion 1033 a in a direction in which the left lower portion 1033 a extends. An upper portion of the left upper portion 1033 b is fixed to a left bracket 1317. A lower portion of the left side member supporting portion 1053A is fixed to the left bracket 1317. The direction in which the left lower portion 1033 a extends is a direction in which the left shock absorber 1033 extends and contracts.

The left lower portion 1033 a and the left upper portion 1033 b each include two telescopic elements. The two telescopic elements are aligned in the front-and-rear direction. The two telescopic elements are connected to each other. This prevents the left lower portion 1033 a from turning relative to the left upper portion 1033 b about an axis parallel to a direction in which the telescopic element extends and contracts.

The right shock absorber 1034 is preferably a so-called telescopic shock absorber and absorbs vibrations caused by the right front wheel 1032 when the right front wheel 1032 receives a load from the road surface. The right shock absorber 1034 includes a right lower portion 1034 a (a right outer element) and a right upper portion 1034 b (a right inner element). The right shock absorber 1034 includes a right side member supporting portion 1054A. The right front wheel 1032 is supported by the right lower portion 1034 a. The right lower portion 1034 a extends in the up-and-down direction of the body frame 1021, and a right wheel axle 1324 is supported at a lower end thereof. The right wheel axle 1324 supports the right front wheel 1032. The right upper portion 1034 b is disposed directly above the right lower portion 1034 a with a portion thereof inserted in the right lower portion 1034 a. The right shock absorber 1034 extends and contracts as a result of the right upper portion 1034 b moving relative to the right lower portion 1034 a in a direction in which the right lower portion 1034 a extends. An upper portion of the right upper portion 1034 b is fixed to a right bracket 1327. A lower portion of the right side member supporting portion 1054A is fixed to the right bracket 1327. The direction in which the right lower portion 1034 a extends is a direction in which the right shock absorber 1034 extends and contracts.

The right lower portion 1034 a and the right upper portion 1034 b each include two telescopic elements. The two telescopic elements are aligned in the front-and-rear direction. The two telescopic elements are connected to each other. This prevents the right lower portion 1034 a from turning relative to the right upper portion 1034 b about an axis parallel to a direction in which the telescopic element extends and contracts.

The steering effort transmission 1006 is disposed above the left front wheel 1031 and the right front wheel 1032 when the vehicle 1001 is viewed from the front thereof with the body frame 1021 being in the upright state. The steering effort transmission 1006 includes a steering member 1028 as a member which inputs a steering effort applied by the rider. The steering member 1028 includes the steering shaft 1060 and a handlebar 1023 which is connected to an upper portion of the steering shaft 1060. The steering shaft 1060 is supported on the headstock 1211 at a portion thereof so as to turn. An upper portion of the steering shaft 1060 is positioned farther rearwards of the body frame 1021 than a lower portion thereof. A turning axis of the steering shaft 1060 extends rearwards and upwards of the body frame 1021. The steering shaft 1060 turns in association with the rider operating the handlebar 1023.

The steering effort transmission 1006 includes the steering member 1028, a tie-rod 1067, the left bracket 1317 and the right bracket 1327. The steering effort transmission 1006 transmits a steering effort by which the rider operates the handlebar 1023 to the left bracket 1317 and the right bracket 1327.

In the present preferred embodiment, the link mechanism 1005 uses a four-joint parallel link (also, referred to as a parallelogram link) system.

The link mechanism 1005 is disposed below the handlebar 1023 when the vehicle 1001 is viewed from the front thereof with the body frame 1021 being in the upright state. The link mechanism 1005 is supported by the headstock 1211 of the body frame 1021. The link mechanism 1005 includes an upper cross member 1051, a lower cross member 1052, a left side member 1053 and a right side member 1054.

The upper cross member 1051 includes a plate-shaped member 1512 which is disposed directly ahead of the headstock 1211 and which extends in a vehicle's width direction. The plate-shaped member 1512 is supported on the headstock 1211 at a middle portion thereof by a support portion C. The support portion C is a boss portion which is provided on the headstock 1211. The upper cross member 1051 is able to turn relative to the headstock 1211 about a middle upper axis which extends in the front-and-rear direction of the body frame 1021. The upper cross member 1051 is able to turn relative to the body frame 1021 about the middle upper axis which extends in the front-and-rear direction of the body frame 1021. The upper cross member 1051 is able to turn relative to the body frame 1021 about the middle upper axis which extends forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021.

A left end of the upper cross member 1051 is supported on the left side member 1053 by a support portion D. The support portion D is a boss portion which is provided on the left side member 1053. The upper cross member 1051 is able to turn relative to the left side member 1053 about a left upper axis which extends in the front-and-rear direction of the body frame 1021. A right end of the upper cross member 1051 is supported on the right side member 1054 by a support portion E. The support portion E is a boss portion which is provided on the right side member 1054. The upper cross member 1051 is able to turn relative to the right side member 1054 about a right upper axis which extends in the front-and-rear direction of the body frame 1021. The middle upper axis, the left upper axis and the right upper axis are parallel to one another. The middle upper axis, the left upper axis and the right upper axis extend forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021.

The lower cross member 1052 is supported on the headstock 1211 at a middle portion thereof by a support portion F. The support portion F is a boss portion which is provided on the headstock 1211. The lower cross member 1052 is able to turn relative to the headstock 1211 about a middle lower axis which extends in the front-and-rear direction of the body frame 1021. The lower cross member 1052 is able to turn relative to the body frame 1021 about the middle lower axis which extends in the front-and-rear direction of the body frame 1021. The lower cross member 1052 is able to turn relative to the body frame 1021 about the middle upper axis which extends forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021. The lower cross member 1052 is disposed below the upper cross member 1051 in the up-and-down direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in the upright state. The lower cross member 1052 has substantially the same length as that of the upper cross member 1051 in the vehicle's width direction. The lower cross member 1052 is disposed parallel to the upper cross member 1051.

The lower cross member 1052 includes a pair of plate-shaped members 1522, 1522 which extend in a left-to-right direction of the vehicle 1001. The pair of plate-shaped members 1522, 1522 is disposed individually directly ahead of and behind the headstock 1211 in the front-and-rear direction of the body frame 1021. The pair of plate-shaped members 1522, 1522 is connected integrally to each other by a connecting portion 1523. The connecting portion 1523 may be integral with or separate from the pair of plate-shaped members 1522, 1522. A left end of the lower cross member 1052 is supported on the left side member 1053 by a support portion G. The support portion G is a boss portion which is provided on the left side member 1053. The lower cross member 1052 is able to turn relative to the left side member 1053 about a left lower axis which extends in the front-and-rear direction of the body frame 1021. A right end of the lower cross member 1052 is supported on the right side member 1054 by a support portion H. The support portion H is a boss portion which is provided on the right side member 1054. The lower cross member 1052 is able to turn relative to the right side member 1054 about a right lower axis which extends in the front-and-rear direction of the body frame 1021. The middle lower axis, the left lower axis and the right lower axis are parallel to one another. The middle lower axis, the left lower axis and the right lower axis extend forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021.

At least a portion of the link mechanism 1005 is able to turn about the middle axes which extend in the front-and-rear direction of the vehicle 1001. At least a portion of the link mechanism 1005 is able to turn about the middle axes (turning axes) which extend forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021. The middle axes (turning axes) lean relative to the horizontal direction. The middle axes (turning axes) lean forwards and upwards relative to the horizontal direction.

The left side member 1053 is disposed directly on the left of the headstock 1211. The left side member 1053 is provided above the left front wheel 1031 and the left shock absorber 1033. The left side member 1053 supports the left side member supporting portion 1053A on an inner circumference thereof so as to turn. The left shock absorber 1033 is able to turn relative to the left side member 1053 about a left center axis Y1. The left center axis Y1 is parallel to a turning axis of the headstock 1211.

The right side member 1054 is disposed directly on the right of the headstock 1211. The right side member 1054 is provided above the right front wheel 1032 and the right shock absorber 1034. The right side member 1054 supports the right side member supporting portion 1054A on an inner circumference thereof so as to turn. The right shock absorber 1034 is able to turn relative to the right side member 1054 about a right center axis Y2. The right center axis Y2 is parallel to the turning axis of the headstock 1211.

In this way, the upper cross member 1051, the lower cross member 1052, the left side member 1053 and the right side member 1054 are supported so that the upper cross member 1051 and the lower cross member 1052 maintain parallel postures to each other, and the left side member 1053 and the right side member 1054 maintain parallel postures to each other.

FIG. 4 is a plan view of the front portion of the vehicle resulting when the vehicle 1001 is steered to be turned, depicting how the vehicle 1001 is steered to be turned. FIG. 4 is a view of the vehicle as viewed from above in the up-and-down direction of the body frame 1021 when the pair of front wheels 1003 are steered with the body frame 1021 being in the upright state.

As shown in FIG. 4 when the handlebar 1023 is turned, the steering effort transmission 1006 of the steering mechanism 1007 is activated so that a steering operation is performed.

For example, when the steering shaft 1060 turns in a direction indicated by an arrow T in FIG. 4, the tie-rod 1067 moves left rearwards. The left bracket 1317 and the right bracket 1327 turn in the direction indicated by the arrow T as the tie-rod 1067 moves left rearwards. When the left bracket 1317 and the right bracket 1327 turn in the direction indicated by the arrow T, the left front wheel 1031 turns about the left center axis Y1 (see FIG. 2), and the right front wheel 1032 turns about the right center axis Y2 (see FIG. 2).

FIG. 5 is a front view of the front portion of the vehicle with the vehicle 1001 caused to lean, illustrating how the vehicle 1001 leans. FIG. 5 is a view of the vehicle 1001 with the body frame 1021 leaning in a leftward direction as viewed from the front thereof in the front-and-rear direction of the vehicle 1001 (the front-and-rear direction of the body frame 1021).

The link mechanism 1005 preferably has a rectangular shape when looking at the vehicle 1001 with the body frame 1021 being in the upright state from the front thereof. The link mechanism 1005 preferably has a parallelogram shape when looking at the vehicle with the body frame 1021 leaning in the leftward direction from the front thereof. The deformation of the link mechanism 1005 is associated with the leaning of the body frame 1021 in the left-and-right direction. The operation of the link mechanism 1005 means that the members of the link mechanism 1005 which are designed to lean (the upper cross member 1051, the lower cross member 1052, the left side member 1053 and the right side member 1054) turn relatively about their support points as turning axes so as to change the shape of the link mechanism 1005.

In the link mechanism 1005 of the present preferred embodiment, for example, the upper cross member 1051, the lower cross member 1052, the left side member 1053 and the right side member 1054, which are disposed substantially in a rectangular shape when the vehicle 1001 which is in the upright state is seen from the front thereof, are deformed substantially into the parallelogram shape when the vehicle 1001 leans. The left front wheel 1031 and the right front wheel 1032 also lean in the left-to-right direction of the vehicle as leaning of the body frame 1021 triggers.

For example, when the rider causes the vehicle 1001 to lean in the leftward direction, the headstock 1211 leans to the left from the vertical direction. When the headstock 1211 leans, the upper cross member 1051 turns about the support portion C relative to the headstock 1211, while the lower cross member 1052 turns about the support portion F relative to the headstock 1211. Then, the upper cross member 1051 moves farther leftwards than the lower cross member 1052, and the left side member 1053 and the right side member 1054 lean from the vertical direction while being kept parallel to the headstock 1211. When the left side member 1053 and the right side member 1054 lean, the left side member 1053 and the right side member 1054 turn relative to the upper cross member 1051 and the lower cross member 1052. Consequently, when the vehicle 1001 is caused to lean, the left front wheel 1031 and the right front wheel 1032 that are supported on the left side member 1053 and the right side member 1054, respectively, lean while being kept parallel to the headstock 1211 relative to the vertical direction as the left side member 1053 and the right side member 1054 lean.

The tie-rod 1067 maintains its parallel posture to the upper cross member 1051 and the lower cross member 1052 even though the vehicle 1001 leans.

In this way, the link mechanism 1005 which leans to cause the left front wheel 1031 and the right front wheel 1032 is disposed directly above the left front wheel 1031 and the right front wheel 1032. Namely, turning shafts of the upper cross member 1051, the lower cross member 1052, the left side member 1053 and the right side member 1054 which define the link mechanism 1005 are disposed above the left front wheel 1031 and the right front wheel 1032.

FIG. 6 is a front view of the front portion of the vehicle with the vehicle 1001 steered and caused to lean. FIG. 6 shows a state in which the vehicle 1001 is steered to the left and is caused to lean to the left. FIG. 6 is a view of the vehicle 1001 as viewed from the front thereof in the front-and-rear direction of the vehicle 1001 (the front-and-rear direction of the body frame 1021) with the pair of left and right front wheels 1003 steered in such a state that the body frame 1021 leans to the left. When the vehicle 1001 is steered in the way described in FIG. 6, due to the steering operation, the left front wheel 1031 and the right front wheel 1032 change their directions, and due to the leaning operation, the left front wheel 1031 and the right front wheel 1032 lean together with the body frame 1021. In this state, the shape defined by the upper cross member 1051, the lower cross member 1052, the left side member 1053 and the right side member 1054 of the link mechanism 1005 is changed into the parallelogram shape, and the tie-rod 1067 moves to the left or right in the direction in which the vehicle 1001 is steered (to the left in FIG. 6) and to the rear.

FIG. 7 is a side view of the left shock absorber 1033 as viewed from a right side of the vehicle 1001 shown in FIG. 1. FIG. 7 is a side view of the left shock absorber 1033 as viewed from a rotating axis of the left front wheel 1031 which is supported by the left shock absorber 1033. In FIG. 7, the left shock absorber 1033 is shown. The right shock absorber 1034 is not shown therein. In the present preferred embodiment, however, the right front wheel 1032 and the right shock absorber 1034 are laterally symmetrical with the left front wheel 1031 and the left shock absorber 1033. Because of this, the reference numerals of the right front wheel 1032 and the right shock absorber 1034 are also given additionally to those of the left front wheel 1031 and the left shock absorber 1033 shown in FIG. 7. Hereinafter, referring to FIG. 7, portions of the right front wheel 1032 and the right shock absorber 1034 will also be described.

The left shock absorber 1033 includes the left lower portion 1033 a (the left outer element) and the left upper portion 1033 b (the left inner element) as shown in FIG. 7. The left shock absorber 1033 includes a left side member supporting portion 1053A. The left lower portion 1033 a and the left upper portion 1033 b include a left rear telescopic element 1331 and a left front telescopic element 1332 which are connected together while being aligned in the front-and-rear direction. The left shock absorber 1033 includes the left rear telescopic element 1331, the left front telescopic element 1332, the left side member supporting portion 1053A and the left bracket 1317 (including a body supporting portion, an inner connecting portion). The left rear telescopic element 1331 extends and contracts in which the left rear telescopic element 1331 extends and contracts in the direction of the left center axis Y1. The left rear telescopic element 1331 includes an elastic member (omitted from illustration) such as a spring and a shock absorbing member (omitted from illustration) such as oil which are provided in an interior thereof. The left rear telescopic element 1331 performs a damper function to absorb vibrations or impacts generated by a load which the left front wheel 1031 receives from the road surface. The left front telescopic element 1332 is disposed on the same side as the side of the left front wheel 1031 where the left rear telescopic element 1331 is disposed in the direction of the rotating axis of the left wheel axle 1314. The left rear telescopic element 1331 and the left front telescopic element 1332 are aligned in the front-and-rear direction on the right of the left front wheel 1031 in the front-and-rear direction of the vehicle 1001 with the vehicle 1001 being in the upright state. The left front telescopic element 1332 is disposed directly ahead of the left rear telescopic element 1331. The left front telescopic element 1332 extends and contracts in which the left front telescopic element 1332 extends and contracts in the direction of the left center axis Y1. The extending and contracting direction of the left rear telescopic element 1331 and the extending and contracting direction of the left front telescopic element 1332 are parallel as viewed from the direction of the rotating axis of the left front wheel 1031. Upper portions of the left rear telescopic element 1331 and the left front telescopic element 1332 are connected together by the left bracket 1317. A lower end portion of the left front telescopic element 1332 is fixedly connected to the vicinity of a lower end portion of the left rear telescopic element 1331. The left wheel axle 1314 of the left front wheel 1031 is provided at a left wheel axle supporting portion 1333 (a wheel supporting portion) which is provided at a lower end portion of the left rear telescopic element 1331. The left front wheel 1031 is supported on the left bracket 1317 by the two telescopic elements of the left rear telescopic elements 1331 and the left front telescopic element 1332 which are aligned in the front-and-rear direction of the vehicle. This prevents the left lower portion 1033 a from turning relative to the left upper portion 1033 b about an axis parallel to a direction in which the telescopic element extends and contracts.

The left bracket 1317 is positioned directly below the front cover 1221 of the body cover 1022 when the vehicle 1001 is viewed from above with the body frame 1021 being in the upright state.

The left front telescopic element 1332 is shorter than the left rear telescopic element 1331 in the extending and contracting direction thereof. A left wheel axle supporting portion 1333 which supports the left wheel axle 1314 is disposed below the lower end portion of the left front telescopic element 1332. The left wheel axle supporting portion 1333 which supports the left wheel axle 1314 is disposed below the left front telescopic element 1332. The left center axis Y1 is positioned between a left rear outer member 1331 a (a left rear outer portion) and a left front outer member 1332 a (a left front outer portion). The left wheel axle supporting portion 1333 is provided on the left rear telescopic element 1331. The left wheel axle supporting portion 1333 is provided on the left rear outer member 1331 a. It is possible to replace the positions of the left rear telescopic element 1331 and the left front telescopic element 1332 in relation to the front-and-rear direction of the vehicle 1001 by rotating them reversely about the left center axis Y1.

The left rear telescopic element 1331 includes a left rear inner member 1331 b (a left rear inner portion) and a left rear outer member 1331 a. The left rear inner member 1331 b defines an upper portion of the left rear telescopic element 1331. The left rear outer member 1331 a defines a lower portion of the left rear telescopic element 1331. The left rear inner member 1331 b is inserted into the left rear outer member 1331 a at a lower portion thereof so as to move relatively. The left front telescopic element 1332 includes a left front inner member 1332 b (a left front inner portion) and a left front outer member 1332 a. The left front inner member 1332 b defines an upper portion of the left front telescopic element 1332. The left front outer member 1332 a defines a lower portion of the left front telescopic element 1332. The left front inner member 1332 b is inserted into the left front outer member 1332 a at a lower portion thereof so as to move relatively. In the left rear telescopic element 1331, a length of a portion where the left rear inner member 1331 b is inserted into the left rear outer member 1331 a is referred to as a left rear insertion length I1. In the left front telescopic element 1332, a length of a portion where the left front inner member 1332 b is inserted into the left front outer member 1332 a is referred to as a left front insertion length I2. In such a state that the left shock absorber 1033 extends to its maximum extent, the left rear insertion length I1 of the left rear telescopic element 1331 is longer than the left front insertion length I2 of the left front telescopic element 1332.

In the event that a vibration or impact is applied thereto from the left front wheel 1031, in the left rear telescopic element 1331, the left rear outer member 1331 a moves in the extending and contracting direction relative to the left rear inner member 1331 b. In the event that a vibration or impact is applied thereto from the left front wheel 1031, in the left front telescopic element 1332, the left front outer member 1332 a moves in the extending and contracting direction relative to the left front inner member 1332 b.

The left rear outer member 1331 a includes a left rear outer main body portion 1331 c (a left rear outer portion), a left rear upper support portion 1331 d, a left rear lower support portion 1331 e, a caliper supporting portion 1331 f and a left wheel axle supporting portion 1333. The left front outer member 1332 a (the left front outer portion) includes a left front outer main body portion 1332 c, a left front upper support portion 1332 d, and a left front lower support portion 1332 e. The left rear outer main body portion 1331 c allows the left rear inner member 1331 b to be inserted thereinto in the extending and contracting direction. The left front outer main body portion 1332 c allows the left front inner member 1332 b to be inserted thereinto in the extending and contracting direction. The left rear upper support portion 1331 d and the left rear lower support portion 1331 e are disposed directly ahead of the left rear outer main body portion 1331 c so as to be aligned in the extending and contracting direction of the left rear telescopic element 1331. The left front upper support portion 1332 d and the left front lower support portion 1332 e are disposed directly ahead of the left front outer main body portion 1332 c so as to be aligned in the extending and contracting direction of the left front telescopic element 1332. The caliper supporting portion 1331 f is disposed behind the left rear outer main body portion 1331 c. The left wheel axle supporting portion 1333 is provided at a lower portion of the left rear outer main body portion 1331 c in the extending and contracting direction of the left rear telescopic element 1331.

The left rear inner member 1331 b and the left front inner member 1332 b are connected together. The left rear inner member 1331 b and the left front inner member 1332 b are connected together by the left bracket 1317. The left rear inner member 1331 b and the left front inner member 1332 b are connected together at upper end portions thereof by the left bracket 1317. The left rear outer member 1331 a and the left front outer member 1332 a are connected together by a plurality of connecting portions. The left rear outer member 1331 a and the left front outer member 1332 a are connected together at a left upper connecting portion 1351 (an outer connecting portion) and a left lower connecting portion 1352 (an outer connecting portion). The left upper connecting portion 1351 and the left lower connecting portion 1352 are aligned in the extending and contracting direction of the left front telescopic element 1332. The left upper connecting portion 1351 is provided at a middle portion of the left front telescopic element 1332 in the extending and contracting direction thereof. The left lower connecting portion 1352 is provided at a lower end portion of the left front telescopic element 1332 in the extending and contracting direction thereof. The left wheel axle supporting portion 1333 is disposed below the left lower connecting portion 1352 in the extending and contracting direction of the left front telescopic element 1332. The left upper connecting portion 1351 includes a left rear upper supporting portion 1331 d, a left front upper supporting portion 1332 d, and a left upper connecting member 1351 a which connects the left rear upper supporting portion 1331 d and the left front upper supporting portion 1332 d together. The left lower connecting member 1352 includes a left rear lower supporting portion 1331 e, a left front lower supporting portion 1332 e and a left lower connecting member 1352 a. The left lower connecting member 1352 a connects the left rear lower supporting portion 1331 e and the left front lower supporting portion 1332 e together.

The left front outer member 1332 a is shorter than the left rear outer member 1331 a in the extending and contracting direction of the left front telescopic element 1332. The left front inner member 1332 b is shorter than the left rear inner member 1331 b in the extending and contracting direction of the left front telescopic element 1332.

Referring to FIG. 7, portions of the right front wheel 1032 and the right shock absorber 1034 will also be described. The right shock absorber 1034 includes a right lower portion 1034 a (a right outer element) and a right upper portion 1034 b (a right inner element). The right shock absorber 1034 includes a right side member supporting portion 1054A. The right lower portion 1034 a and the right upper portion 1034 b include a right rear telescopic element 1341 and a right front telescopic element 1342 which are connected together so as to be aligned in the front-and-rear direction. The right shock absorber 1034 includes a right rear telescopic element 1341, a right front telescopic element 1342, the right side member supporting portion 1054A and the right bracket 1327 (the body support portion, the inner connecting portion). The right rear telescopic element 1341 extends and contracts such that the right rear telescopic element 1341 extends and contracts in the direction of the right center axis Y2. An elastic member (omitted from illustration) such as a spring or the like and a damping member (omitted from illustration) such as oil or the like are provided in an interior of the right rear telescopic element 1341. The right rear telescopic element 1341 performs a damper function to absorb vibrations or impacts generated by a load which the right front wheel 1032 receives from the road surface. The right front telescopic element 1342 is disposed on the same side as the side of the right front wheel 1032 where the right rear telescopic element 1341 is disposed in the direction of the rotating axis of the right wheel axle 1324. The right rear telescopic element 1341 and the right front telescopic element 1342 are aligned in the front-and-rear direction on the right of the right front wheel 1032 with the vehicle 1001 being in the upright state. The right front telescopic element 1342 is disposed directly ahead of the right rear telescopic element 1341. The right front telescopic element 1342 extends and contracts such that the right front telescopic element 1342 extends and contracts in the direction of the right center axis Y2. The extending and contracting direction of the right rear telescopic element 1341 and the extending and contracting direction of the right front telescopic element 1342 are parallel as viewed from the direction of the rotating axis of the right front wheel 1032. Upper portions of the right rear telescopic element 1341 and the right front telescopic element 1342 are connected together by the right bracket 1327. A lower end portion of the right front telescopic element 1342 is fixedly connected to the vicinity of a lower end portion of the right rear telescopic element 1341. The right wheel axle 1324 of the right front wheel 1032 is supported on the right wheel axle supporting portion 1343 (the wheel supporting portion) which is provided at the lower end portion of the right rear telescopic element 1341. The right front wheel 1032 is supported on the right bracket 1327 by the two telescopic elements of the right rear telescopic elements 1341 and the right front telescopic element 1342 which are aligned in the front-and-rear direction of the vehicle. This prevents the right lower portion 1034 a from turning relative to the right upper portion 1034 b about an axis parallel to a direction in which the telescopic element extends and contracts.

The right bracket 1327 is positioned directly below the front cover 1221 of the body cover 1022 when the vehicle 1001 is viewed from above with the body frame 1021 being in the upright state.

The right front telescopic element 1342 is shorter than the right rear telescopic element 1341 in the extending and contracting direction thereof. A right wheel axle supporting portion 1343 which supports rotatably the right wheel axle 1324 is disposed below the lower end portion of the right front telescopic element 1342. The right wheel axle supporting portion 1343 which supports rotatably the right wheel axle 1324 is disposed below the right front telescopic element 1342. The right center axis Y2 is positioned between a right rear outer member 1341 a (a right rear outer portion) and a right front outer member 1342 a (a right front outer portion). The right wheel axle supporting portion 1343 is provided on the right rear telescopic element 1341. The right wheel axle supporting portion 1343 is provided on the right rear outer member 1341 a. It is possible to replace the positions of the right rear telescopic element 1341 and the right front telescopic element 1342 in relation to the front-and-rear direction of the vehicle 1001 by rotating them reversely about the right center axis Y2.

The right rear telescopic element 1341 includes a right rear inner member 1341 b (a right rear inner portion) and a right rear outer member 1341 a. The right rear inner member 1341 b defines an upper portion of the right rear telescopic element 1341. The right rear outer member 1341 a defines a lower portion of the right rear telescopic element 1341. The right rear inner member 1341 b is inserted into the right rear outer member 1341 a at a lower portion thereof so as to move relatively. The right front telescopic element 1342 includes a right front inner member 1342 b (a right front inner portion) and a right front outer member 1342 a. The right front inner member 1342 b defines an upper portion of the right front telescopic element 1342. The right front outer member 1342 a defines a lower portion of the right front telescopic element 1342. The right front inner member 1342 b is inserted into the right front outer member 1342 a at a lower portion thereof so as to move relatively. In the right rear telescopic element 1341, a length of a portion where the right rear inner member 1341 b is inserted into the right rear outer member 1341 a is referred to as a right rear insertion length I3. In the right front telescopic element 1342, a length of a portion where the right front inner member 1342 b is inserted into the right front outer member 1342 a is referred to as a right front insertion length I4. In such a state that the right shock absorber 1034 extends to its maximum extent, the right rear insertion length I3 of the right rear telescopic element 1341 is longer than the right front insertion length I4 of the right front telescopic element 1342.

In the event that a vibration or impact is applied thereto from the right front wheel 1032, in the right rear telescopic element 1341, the right rear outer member 1341 a moves in the extending and contracting direction relative to the right rear inner member 1341 b. In the event that a vibration or impact is applied thereto from the right front wheel 1032, in the right front telescopic element 1342, the right front outer member 1342 a moves in the extending and contracting direction relative to the right front inner member 1342 b.

The right rear outer member 1341 a includes a right rear outer main body portion 1341 c (a right rear outer portion), a right rear upper support portion 1341 d, a right rear lower support portion 1341 e, a caliper supporting portion 1341 f and a right wheel axle supporting portion 1343. The right front outer member 1342 a (the right front outer portion) includes a right front outer main body portion 1342 c, a right front upper support portion 1342 d, and a right front lower support portion 1342 e. The right rear outer main body portion 1341 c allows the right rear inner member 1341 b to be inserted thereinto in the extending and contracting direction. The right front outer main body portion 1342 c allows the right front inner member 1342 b to be inserted thereinto in the extending and contracting direction. The right rear upper support portion 1341 d and the right rear lower support portion 1341 e are disposed directly ahead of the right rear outer main body portion 1341 c so as to be aligned in the extending and contracting direction of the right rear telescopic element 1341. The right front upper support portion 1342 d and the right front lower support portion 1342 e are disposed directly behind of the right front outer main body portion 1342 c so as to be aligned in the extending and contracting direction of the right front telescopic element 1342. A caliper supporting portion 1341 f is disposed behind the right rear outer main body portion 1341 c. The right wheel axle supporting portion 1343 is provided at a lower portion of the right rear outer main body portion 1341 c in the extending and contracting direction of the right rear telescopic element 1341.

The right rear inner member 1341 b and the right front inner member 1342 b are connected together. The right rear inner member 1341 b and the right front inner member 1342 b are connected together by the right bracket 1327. The right rear inner member 1341 b and the right front inner member 1342 b are connected together at upper end portions thereof by the right bracket 1327. The right rear outer member 1341 a and the right front outer member 1342 a are connected together by a plurality of connecting portions. The right rear outer member 1341 a and the right front outer member 1342 a are connected together at a right upper connecting portion 1353 (an outer connecting portion) and a right lower connecting portion 1354 (an outer connecting portion). The right upper connecting portion 1353 and the right lower connecting portion 1354 are aligned in the extending and contracting direction of the right front telescopic element 1342. The right upper connecting portion 1353 is provided at a middle portion of the right front telescopic element 1342 in the extending and contracting direction thereof. The right lower connecting portion 1354 is provided at a lower end portion of the right front telescopic element 1342 in the extending and contracting direction thereof. The right wheel axle supporting portion 1343 is disposed below the right lower connecting portion 1354 in the extending and contracting direction of the right front telescopic element 1342. The right upper connecting portion 1353 includes a right rear upper supporting portion 1341 d, a right front upper supporting portion 1342 d, and a right upper connecting member 1353 a which connects the right rear upper supporting portion 1341 d and the right front upper supporting portion 1342 d together. The right lower connecting member 1354 includes a right rear lower supporting portion 1341 e, a right front lower supporting portion 1342 e and a right lower connecting member 1354 a. The right lower connecting member 1354 a connects the right rear lower supporting portion 1341 e and the right front lower supporting portion 1342 e together.

The right front outer member 1342 a is shorter than the right rear outer member 1341 a in the extending and contracting direction of the right front telescopic element 1342. The right front inner member 1342 b is shorter than the right rear inner member 1341 b in the extending and contracting direction of the right front telescopic element 1342.

As shown in FIG. 7, the left front wheel 1031 includes a left front brake 1071. The left front brake 1071 generates a braking force for the left front wheel 1031. The left front brake 1071 includes a left brake disc 1711 and a left caliper 1712. The left brake disc 1711 preferably has a ring shape which is centered at the left wheel axle 1314. The left brake disc 1711 is fixed to the left front wheel 1031. The left caliper 1712 is provided on the left shock absorber 1033. The left caliper 1712 is fixed to a lower portion of the left rear telescopic element 1331 of the left shock absorber 1033. The left caliper 1712 is fixed to the caliper supporting portion 1331 f. The left caliper 1712 is disposed directly behind the lower portion of the left rear telescopic element 1331 of the left shock absorber 1033. A left brake hose 1714 is connected to the left caliper 1712 at one end portion thereof. The left caliper 1712 receives a hydraulic pressure via the left brake hose 1714. The left caliper 1712 moves brake pads due to the hydraulic pressure which the left caliper 1712 has received. The brake pads are brought into contact with a right side surface and a left side surface of the left brake disc 1711. The left caliper 1712 applies a brake to the rotation of the left brake disc 1711 by holding the left brake disc 1711 by the brake pads.

Referring to FIG. 7, constituent portions of the right front wheel 1032 will also be described. The right front wheel 1032 includes a right front brake 1072. The right front brake 1072 generates a braking force on the right front wheel 1032. The right front brake 1072 includes a right brake disc 1721 and a right caliper 1722. The right brake disc 1721 preferably has a ring shape which is centered at the right wheel axle 1324. The right brake disc 1721 is fixed to the right front wheel 1032. The right caliper 1722 is provided on the right shock absorber 1034. The right caliper 1722 is fixed to a lower portion of the right rear telescopic element 1341 of the right shock absorber 1034. The right caliper 1722 is fixed to a caliper supporting portion 1341 f. The right caliper 1722 is disposed at the lower portion of the right rear telescopic element 1341 of the right shock absorber 1034. One end portion of a right front brake hose 1724 is connected to the right caliper 1722. The right caliper 1722 receives a hydraulic pressure via the right front brake hose 1724. The right caliper 1722 moves brake pads due to the hydraulic pressure which the right caliper 1722 receives. The brake pads are brought into contact with a left side surface and a right side surface of the right brake disc 1721. The right caliper 1722 holds the right brake disc 1721 with the brake pads to brake the rotation of the right brake disc 1721.

As shown in FIG. 7, a left wheel speed sensor 1081 (an example of a body structure) includes a left sensor disc 1811 and a left detector 1812 (an example of a left front wheel slip detector). The left sensor disc 1811 preferably has a ring shape which is centered at the left wheel axle 1314. The left sensor disc 1811 is smaller in diameter than the left brake disc 1711. The left sensor disc 1811 is disposed on an inner circumference of the left brake disc 1711. The left sensor disc 1811 is fixed to the left front wheel 1031. The left detector 1812 detects a rotation of the left sensor disc 1811 optically or magnetically. The left detector 1812 generates an electric signal which changes according to the rotating speed of the left sensor disc 1811. Alternatively, the left detector 1812 changes the electric signal according to the rotating speed of the left sensor disc 1811. The left detector 1812 includes a left sensor cord 1813. An electric signal generated or changed in the left detector 1812 is transmitted to the controller by way of the left sensor cord 1813. A rotating wheel speed of the left front wheel 1031 is calculated based on the electric signal in the left detector 1812 which is transmitted by way of the left sensor cord 1813.

A left sensor stay 1814 is fixed to the left wheel axle supporting portion 1333. The left detector 1812 of the left wheel speed sensor 1081 is supported on the left sensor stay 1814. The left sensor stay 1814 has enough rigidity for the detection accuracy of the left detector 1812 of the left wheel speed sensor 1081 to be maintained even though the left shock absorber 1033 vibrates while the vehicle 1001 is running.

When looking at the left front wheel 1031 from the center in the vehicle's width direction, the left shock absorber 1033 includes a left area 1336 which is defined by the left rear telescopic element 1331, the left front telescopic element 1332, the left bracket 1317, and an imaginary line 1335 which connects the lower end portion of the left rear telescopic element 1331 and the lower end portion of the left front telescopic element 1332. The left detector 1812 of the left wheel speed sensor 1081 is disposed outwards of the left area 1336. The left detector 1812 is disposed below the left area 1336. The left detector 1812 is disposed ahead of the left area 1336. The left detector 1812 is disposed above the lower end portion of the left rear telescopic element 1331.

As viewed from the direction of the rotating axis of the left front wheel 1031 which is supported by the left wheel axle supporting portion 1333, a step portion 1361 is defined by the left rear telescopic element 1331 and the left front telescopic element 1332. The step portion 1361 is defined by the left rear outer member 1331 a (the left rear outer portion) and the left front outer member 1332 a (the left front outer portion). The left sensor stay 1814 is disposed at the step portion 1361.

As viewed from the direction of the rotating axis of the left front wheel 1031 which is supported by the left wheel axle supporting portion 1333, the left detector 1812 of the left wheel speed sensor 1081 is disposed ahead of the left caliper 1712. The left detector 1812 of the left wheel speed sensor 1081 is disposed ahead of the left wheel axle 1314. The left detector 1812 is disposed at least partially directly below the left front telescopic element 1332 in the extending and contracting direction of the left front telescopic element 1332.

Referring to FIG. 7, constituent portions of the right front wheel 1032 will also be described. A right wheel speed sensor 1082 (an example of a body part) includes a right sensor disc 1821 and a right detector 1822 (an example of a right front wheel slip detector). The right sensor disc 1821 preferably has a ring shape which is centered at the right wheel axle 1324. The right sensor disc 1821 is smaller in diameter than the right brake disc 1721. The right sensor disc 1821 is disposed on an inner circumference of the right brake disc 1721. The right sensor disc 1821 is fixed to the right front wheel 1032. The right detector 1822 detects a rotation of the right sensor disc 1821 optically or magnetically. The right detector 1822 generates an electric signal which changes according to the rotating speed of the right sensor disc 1821. Alternatively, the right detector 1822 changes the electric signal according to the rotating speed of the right sensor disc 1821. The right detector 1822 includes a right sensor cord 1823. An electric signal generated or changed in the right detector 1822 is transmitted to the controller by way of the right sensor cord 1823. A rotating wheel speed of the right front wheel 1032 is calculated based on the electric signal in the right detector 1822 which is transmitted by way of the right sensor cord 1823.

A right sensor stay 1824 is fixed to the right wheel axle supporting portion 1343. The right detector 1822 of the right wheel speed sensor 1082 is supported on the right sensor stay 1824. The right sensor stay 1824 has enough rigidity for the detection accuracy of the right detector 1822 of the right wheel speed sensor 1082 to be maintained even though the right shock absorber 1034 vibrates while the vehicle 1001 is running.

When looking at the right front wheel 1032 from the center in the vehicle's width direction, the right shock absorber 1034 includes a right area 1346 which is defined by the right rear telescopic element 1341, the right front telescopic element 1342, the right bracket 1327, and an imaginary line 1345 which connects the lower end portion of the right rear telescopic element 1341 and the lower end portion of the right front telescopic element 1342. The right detector 1822 of the right wheel speed sensor 1082 is disposed outwards of the right area 1346. The right detector 1822 is disposed below the right area 1346. The right detector 1822 is disposed ahead of the right area 1346. The right detector 1822 is disposed above the lower end portion of the right rear telescopic element 1341.

As viewed from the direction of the rotating axis of the right front wheel 1032 which is supported by the right wheel axle supporting portion 1343, a step portion 1362 is defined by the right rear telescopic element 1341 and the right front telescopic element 1342. The step portion 1362 is defined by the right rear outer member 1341 a (the right rear outer portion) and the right front outer member 1342 a (the right front outer portion). The right sensor stay 1824 is disposed at the step portion 1362.

As viewed from the direction of the rotating axis of the right front wheel 1032 which is supported by the right wheel axle supporting portion 1343, the right detector 1822 of the right wheel speed sensor 1082 is disposed ahead of the right caliper 1722. The right detector 1822 of the right wheel speed sensor 1082 is disposed ahead of the right wheel axle 1324. The right detector 1822 is disposed at least a partially directly below the right front telescopic element 1342 in the extending and contracting direction of the right front telescopic element 1342.

FIGS. 8A and 8B are diagrams showing positions of the vehicle and wheels in the front-and-rear direction as viewed from above in the up-and-down direction of the body frame. In the following description, as a matter of convenience, there may be a situation in which FIGS. 8A and 8B are collectively be referred to as FIG. 8. The vehicle of which the body frame is in the upright state is shown at (a) of FIG. 8A. As this occurs, none of the brakes on the right front wheel, the left front wheel and the central rear wheel is in operation. The vehicle shown at (b) of FIGS. 8A and 8B is turning with the body frame leaning to the left in the left-to-right direction of the vehicle. As this occurs, although neither of the brakes on the right front wheel and the left front wheel is in operation, the brake on the central rear wheel is in operation. The vehicle shown at (c) of FIG. 8B is turning with the body frame leaning to the left in the left-and-right direction of the vehicle. As this occurs, the brakes on the right front wheel and the left front wheel are in operation. For the purpose of facilitating comparison between (a) and (b) in FIG. 8 and between (b) and (c) in FIG. 8, (b) is shown in both FIGS. 8A and 8B.

(a) in FIG. 8A shows the vehicle with the body frame being in the upright state. As this occurs, none of the brakes on the right front wheel, the left front wheel and the central rear wheel is in operation. The vehicle 1001 includes a brake system 1702. The vehicle 1001 includes the body frame 1021. The vehicle 1001 includes the right front wheel 1032 and the left front wheel 1031 which are aligned side by side in the left-and-right direction of the body frame 1021 when the vehicle 1001 with the body frame 1021 being in the upright state is viewed from the front thereof. The vehicle 1001 includes a central rear wheel 1004 which is provided behind the right front wheel 1032 and the left front wheel 1031 in the front-and-rear direction of the body frame 1021 and which is disposed between the right front wheel 1032 and the left front wheel 1031 when the vehicle 1001 is viewed from the front thereof with the body frame 1021 being in the upright state. The right shock absorber 1034 supports the right front wheel 1032 at a lower portion thereof. The right shock absorber 1034 absorbs an upward displacement of the right front wheel 1032 in the up-and-down direction of the body frame 1021. The left shock absorber 1033 supports the left front wheel 1031 at a lower portion thereof. The left shock absorber 1033 absorbs an upward displacement of the left front wheel 1031 in the up-and-down direction of the body frame 1021. The link mechanism 1005 is provided above the right front wheel 1032 and the left front wheel 1031 in the up-and-down direction of the body frame 1021 when the vehicle is viewed from the front thereof with the body frame 1021 being in the upright state. The link mechanism 1005 supports an upper portion of the right shock absorber 1034 and an upper portion of the left shock absorber 1033 so as to turn. The link mechanism 1005 is supported at least partially on the body frame 1021 so as to turn about a turning axis which extends forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-and-down direction of the body frame 1021. The brake system 1702 includes a right front brake 1072 which is provided on the right front wheel 1032 and which generates a braking force on the right front wheel 1032. The brake system 1702 includes a left front brake 1071 which is provided on the left front wheel 1031 and which generates a braking force on the left front wheel 1031. The brake system 1702 includes an input member 1751 which the rider who rides the vehicle 1001 operates with his or her hand. The input member 1751 is preferably a lever. The brake system 1702 includes a brake activator 1756. The brake activator 1756 activates the right front brake 1072 and the left front brake 1071. The brake system 1702 includes the right detector 1822 that detects a right front wheel's slipping condition. The brake system 1702 includes the left detector 1812 that detects a left front wheel's slipping condition. The brake system 1702 includes a rear detector 1832 that detects a slipping condition of the central rear wheel 1004 (refer to FIG. 8(a)).

The brake activator 1756 operates in the following manner while the vehicle is turning with the body frame 1021 leaning in the left-and-right of the vehicle and the right front brake 1072 and the left front brake 1071 are both in operation as a result of operation of the input member 1751. When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the right detector 1822. In addition, the brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822. When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the brake activator 1756 reduces a braking force on the right front wheel 1032 and a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling both the operating condition of the right front brake 1072 on the right front wheel 1032 and the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822. When a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the left detector 1812. In addition, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812. When a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the brake activator 1756 reduces a braking force on the left front wheel 1031 and a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling both the operating condition of the left front brake 1071 on the left front wheel 1031 and the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812. The braking force which is obtained as a result of operation of the input member 1751 changes with operation quantity of the input member 1751. In the present preferred embodiment, the “braking force which is obtained as a result of input member” refers to a braking force which would then originally be obtained based on an operation quantity of the input member.

The right front brake 1072 and left front brake 1071 are activated by operation of the input member 1751 when the vehicle is turning with the body frame 1021 leaning to the left of the vehicle. The right front brake 1072 and the left front brake 1071 generate a right braking force FRFW and a left braking force FLFW, respectively (refer to FIG. 8(b)). As this occurs, the hydraulic pressure controller 1755 determines a slipping condition of the right front wheel 1032 based on a signal detected by the right detector 1822. In the present preferred embodiment, the right detector 1822 generates a pulsed electric signal which is associated with a rotation of the right front wheel 1032. Upon receipt of this signal, the hydraulic pressure controller 1755 determines a slipping condition of the right front wheel 1032 based on the signal and the like. The “slipping condition” refers to a condition in which the rotating wheel fails to make proper contact with the road surface. A threshold by which a slipping condition is determined is arbitrarily be set based on conditions of the vehicle, characteristics of the vehicle, and the like. In case it is determined that the right front wheel 1032 is slipping, the hydraulic pressure controller 1755 controls the right front brake 1072 according to the slipping condition of the right front wheel 1032. As a result, the right braking force FRFW on the right front wheel 1032 reduces to a lower level than a level of a right braking force FRFW which is obtained as a result of operation of the input member 1751. In addition, in case it is determined that the right front wheel 1032 is slipping, the hydraulic pressure controller 1755 controls the operating condition of the left front brake 1071 according to the slipping condition of the right front wheel 1032. As a result, the left braking force FLFW on the left front wheel 1031 also reduces to a lower level than a level of a left braking force FLFW which is obtained as a result of operation of the input member 1751. This restricts a difference between the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 from becoming large (refer to FIG. 8(c)). As this is occurring, the reduction in the right braking force FRFW on the right front wheel 1032 is smaller than the reduction in the left braking force FLFW on the left front wheel 1031. The reduction in the right braking force FRFW on the right front wheel 1032 may be equal to the reduction in the left braking force FLFW on the left front wheel 1031. Additionally, the reduction in the right braking force FRFW on the right front wheel 1032 may be larger than the reduction in the left braking force FLFW on the left front wheel 1031. Although FIGS. 8(b) and (c) show the case where the vehicle is turning with the body frame 1021 leaning to the left of the vehicle, in the case of the vehicle turning with the body frame 1021 leaning to the right of the vehicle, only the front wheels which defines the inner wheel and the outer wheel are replaced, and the other features remain the same.

The right front brake 1072 and left front brake 1071 are activated as a result of operation of the input member 1751 when the vehicle is turning with the body frame 1021 leaning to the left of the vehicle. The right front brake 1072 and the left front brake 1071 generate a right braking force FRFW and a left braking force FLFW, respectively (refer to FIG. 8(b)). As this occurs, the hydraulic pressure controller 1755 determines a slipping condition of the left front wheel 1031 based on a signal detected by the left detector 1812. In the present preferred embodiment, the left detector 1812 generates a pulsed electric signal which is associated with a rotation of the left front wheel 1031. Upon receipt of this signal, the hydraulic pressure controller 1755 determines a slipping condition of the left front wheel 1031 based on the signal and the like. For example, the hydraulic pressure controller 1755 determines a slipping condition by comparing a variation in speed or quantity of the rotating speed of the left front wheel 1031 with a threshold which is determined experimentally in advance. The slipping condition includes not only a condition in which the wheel slips completely but also a condition in which the rotating speed drops drastically prior to the occurrence of slip. In case it is determined that the left front wheel 1031 is slipping, the hydraulic pressure controller 1755 controls the operating condition of the left front brake 1071 according to the slipping condition of the left front wheel 1031. As a result, the left braking force FLFW on the left front wheel 1031 reduces to a lower level than a level of a left braking force FLFW which is obtained as a result of operation of the input member 1751. In addition, in case it is determined that left front wheel 1031 is slipping, the hydraulic pressure controller 1755 controls the operating condition of the right front brake 1072 according to the slipping condition of the left front wheel 1031. As a result, the right braking force FRFW on the right front wheel 1032 also reduces to a lower level than a level of a right braking force FRFW which is obtained as a result of operation of the input member 1751. This restricts a difference between the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 from becoming large. As this is occurring (refer to FIG. 8(c)), the reduction in the right braking force FRFW on the right front wheel 1032 is smaller than the reduction in the left braking force FLFW on the left front wheel 1031. The reduction in the right braking force FRFW on the right front wheel 1032 may be equal to the reduction in the left braking force FLFW on the left front wheel 1031. Additionally, the reduction in the right braking force FRFW on the right front wheel 1032 may be larger than the reduction in the left braking force FLFW on the left front wheel 1031. In FIGS. 8(a), (b) and (c), the vehicle is illustrated as turning to the left with the body frame 1021 leaning to the left of the vehicle. In the case of the vehicle turning with the body frame 1021 leaning to the right of the vehicle, the front wheels which define the inner wheel and the outer wheel are replaced. Left and right and inner and outer in the above description should be read in a reversed manner. The others are basically the same.

The vehicle 1001 includes the brake system 1702. The brake system 1702 includes the input member 1751. The brake system 1702 includes a brake activator 1756. The brake activator 1756 includes a front master cylinder 1753 r. When the rider operates the input member 1751, the front master cylinder 1753 r is activated to generate a hydraulic pressure. The hydraulic pressure generated is then transmitted to the hydraulic pressure controller 1755 by way of the front brake hose 1704. The hydraulic pressure controller 1755 transmits a hydraulic pressure, corresponding to the hydraulic pressure transmitted thereto, to the right caliper 1722 by way of the right front brake hose 1724. This activates the right front brake 1072. The hydraulic pressure controller 1755 transmits a hydraulic pressure corresponding to the hydraulic pressure transmitted thereto to the left caliper 1712 by way of the left brake hose 1714. This activates the left front brake 1071.

The brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 according to a physical quantity in relation to the braking force on the right front wheel 1032 based on the signal detected by the right detector 1822. The brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating conditions of the right front brake 1072 on the right front wheel 1032 according to a physical quantity in relation to the braking force on the left front wheel 1031 based on the signal detected by the left detector 1812. The signals which are detected by the right detector 1822 and the left detector 1812 are not processed directly but are controlled according to a physical quantity in relation to the braking forces in the front wheels which is an indirect physical quantity based on the signals detected by the detectors. The physical quantity in relation to braking force is preferably calculated from a quantity of torque which is borne by the axles of the front wheels. The physical quantity in relation to braking force may be calculated from a variation in rotating speed of the front wheels. The physical quantity in relation to braking force may be calculated from a hydraulic pressure which is transmitted to the brake of each front wheel. The physical quantity in relation to braking force is a physical quantity which acts to restrict the increase in difference between the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031, including the physical quantity itself, a variation in physical quantity, a variation speed of physical quantity, a difference in physical quantity (for example, a difference in hydraulic pressure, variation in hydraulic pressure, variation speed of hydraulic pressure, a difference from another hydraulic pressure, and the like) and the like. The physical quantity is detected by the sensor and is converted into an electric signal which is generated by the sensor.

The brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 according to a physical quantity in relation to the operating condition of the right front brake 1072 based on the signal detected by the right detector 1822. In addition, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 according to a physical quantity in relation to the operating condition of the left front brake 1071 based on the signal detected by the left detector 1812. The signals detected by the slip detectors are not processed directly but are controlled according to the physical quantities in relation to the operating condition of the front brake which are the indirect physical quantities based on the signals detected by the slip detectors. The physical quantity in relation to the operating condition of the front brake may be calculated from an operation quantity of an actuator which controls a hydraulic pressure to be transmitted to the front brakes. The physical quantity in relation to the operating condition of the front brake may be calculated from a hydraulic pressure which is transmitted to the brake of each front wheel. The physical quantity in relation to the operating condition of the front brake is a physical quantity which acts to restrict the increase in difference between the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031, including the physical quantity itself, a variation in physical quantity, a variation speed of physical quantity, a difference in physical quantity (for example, a difference in hydraulic pressure, variation in hydraulic pressure, variation speed of hydraulic pressure, a difference from another hydraulic pressure, and the like) and the like. The physical quantity in relation to the operating condition of the front brake is included in the physical quantity in relation to braking force. The physical quantity is detected by the sensor and is converted into an electric signal which is generated by the sensor.

The brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 according to a control quantity by which the operating condition of the right front brake 1072 is controlled based on a signal which is detected by the right detector 1822. In addition, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 according to a control quantity by which the operating condition of the left front brake 1071 is controlled based on a signal which is detected by the left detector 1812. The signals detected by the slip detectors are not processed directly but are processed according to the control quantities which are indirect electric signals based on the signals detected by the slip detectors and by which the operating conditions of the front brake are controlled. The control quantity by which the operating condition of the front brake is controlled may be calculated from a command signal or command current to the actuator which controls a hydraulic pressure to be transmitted to the front brake. The control quantity by which the operating condition of the front brake is controlled is an electric signal which acts to restrict the increase in difference between the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031, including the electric signal itself, a variation in electric signal, a variation speed of electric signal, a difference in electric signal (for example, a difference in command value, variation in command value, variation speed of command value, a difference from a other command value and the like) and the like. Controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822 includes controlling the operating condition of the left front brake 1071 directly according to the signal detected by the right detector 1822. In addition, controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822 includes controlling the operating condition of the left front brake 1071 indirectly according to the physical quantity and the electric signal which correspond to the signal which is detected by the right detector 1822. Controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812 includes controlling the operating condition of the right front brake 1072 directly according to the signal detected by the left detector 1812. Controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812 includes controlling the operating condition of the right front brake 1072 indirectly according to the physical quantity and the electric signal which correspond to the signal which is detected by the left detector 1812.

When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the brake activator 1756 reduces first a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032. Then, the brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822. In addition, when a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the brake activator 1756 reduces first a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031. Then, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812. While the vehicle is turning with the body frame 1021 leaning and both the right front brake 1072 and the left front brake 1071 are in operation, the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 are reduced with a certain time lag by controlling the operating conditions of both the right front brake 1072 and the left front brake 1071 based on the detection signal of one of the right detector 1822 and the left detector 1812. This restricts a total braking force of the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 from changing with time.

When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the brake activator 1756 reduces the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 at the same time to a lower level than a level of a braking force which is obtained as a result of the operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 and controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822. In addition, when a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the brake activator 1756 reduces the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 at the same time to a lower level than a level of a braking force which is obtained as a result of the operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 and controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812. While the vehicle is turning with the body frame 1021 leaning and both the right front brake 1072 and the left front brake 1071 are in operation, the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 are reduced at the same time by controlling the operating conditions of both the right front brake 1072 and the left front brake 1071 based on the detection signal of one of the right detector 1822 and the left detector 1812. This restricts a difference in total braking force of the right braking force FRFW on the right front wheel 1032 and the left braking force FLFW on the left front wheel 1031 from becoming large.

In the vehicle 1001, the right shock absorber 1034 includes the right telescopic element 1341 (1342) that extends and contracts in the extending and contracting direction which extends in the up-and-down direction of the body frame 1021 and allows the right front wheel 1032 to be displaced in the extending and contracting direction of the right telescopic element 1341 (1342). The left shock absorber 1033 includes the left telescopic element 1331 (1332) that extends and contracts in the extending and contracting direction which extends in the up-and-down direction of the body frame 1021 and allows the left front wheel 1031 to be displaced in the extending and contracting direction of the left telescopic element 1331 (1332).

The link mechanism 1005 is provided above the right front wheel 1032 and the left front wheel 1031 in the up-and-down direction of the body frame 1021 as viewed from the front of the vehicle with the body frame 1021 being in the upright state. The right front wheel 1032 and the left front wheel 1031 overlap the central rear wheel 1004 when the vehicle is viewed from the front thereof with the body frame 1021 leaning in the left-and-right direction of the vehicle and the right shock absorber 1034 and the left shock absorber 1033 turning most relative to the link mechanism 1005 as shown in FIG. 6. Also, when the vehicle is viewed from the front thereof with the up-and-down direction of the body frame 1021 coinciding with the vertical direction and the right shock absorber 1034 and the left shock absorber 1033 turning most relative to the link mechanism 1005, the right front wheel 1032 and the left front wheel 1031 overlap the central rear wheel 1004.

The vehicle 1001 includes a second brake system 1701. The second brake system 1701 includes a second input member 1752 which differs from the input member 1751. The second brake system 1701 includes a second brake activator 1754. The second brake activator 1754 includes a rear master cylinder 17531. The rear master cylinder 17531 is connected to the hydraulic pressure controller 1755 which defines a portion of the brake activator 1756 by way of the rear brake hose 1734. The second brake activator 1754 includes the hydraulic pressure controller 1755 which defines a portion of the brake activator 1756. The second brake activator 1756 activates the right front brake 1072, the left front brake 1071 and the central rear brake 1073 as a result of operation of the second input member 1752. When the second input member 1752 is operated, the rear master cylinder 17531 is activated to generate a hydraulic pressure. The hydraulic pressure generated in the rear master cylinder 17531 is transmitted to the hydraulic pressure controller 1755 which defines a portion of the brake activator 1756 and the second brake activator 1754 by way of the rear brake hose 1734. The hydraulic pressure controller 1755 transmits a hydraulic pressure, corresponding to the hydraulic pressure transmitted thereto, to the right caliper 1722 by way of the right front brake hose 1724. This activates the right front brake 1072. The hydraulic pressure controller 1755 transmits a hydraulic pressure corresponding to the hydraulic pressure transmitted thereto to the left caliper 1712 by way of the left brake hose 1714. This activates the left front brake 1071. The hydraulic pressure controller 1755 transmits a hydraulic pressure corresponding to the hydraulic pressure transmitted thereto to the central rear caliper 1732 by way of the rear brake hose 1734. This activates the central rear brake 1073. The second brake activator 1754 activates the right front brake 1072 and the left front brake 1071 by using at least a portion of the brake activator 1756. The second brake activator 1754 activates the right front brake 1072 and the left front brake 1071 by using at least a portion of the brake activator 1756. As this occurs, timings at which braking forces are generated on the right front wheel 1032, the left front wheel 1031 and the central rear wheel 1004 as a result of operation of the right front brake 1072, the left front brake 1071 and the central rear brake 1073 and magnitudes of the braking forces generated are set as required. The timings may be the same as or different from one another. The magnitudes may increase in the same way or differently.

FIG. 9 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 8. FIG. 9 shows the brake system 1702 shown in FIG. 8 in detail. The hydraulic pressure controller 1755 includes an electronic controller 1755 a and a hydraulic pressure unit which is activated by the electronic controller 1755 a. The right detector 1822 is connected to the electronic controller 1755 a via the right sensor cord 1823. The left detector 1812 is connected to the electronic controller 1755 a via the left sensor cord 1813. A rear detector 1832 is a sensor that detects a rotation of a rear sensor disc 1831. The function of the rear detector 1832 is the same as the functions of the right detector 1822 and the left detector 1812. The rear detector 1832 is connected to the electronic controller 1755 a via a rear sensor cord 1833. The electronic controller 1755 a receives electric signals from the rear detector 1832, the right detector 1822 and the left detector 1812. Then, the electronic controller 1755 a detects a rotating speed of each wheel from an electric signal therefrom. The electronic controller 1755 a also receives electric signals in relation to vehicle speed, vehicle posture, vehicle acceleration and the like from other sensors (not shown) than those described above. The brake activator 1756 includes a front master cylinder 1753 r. When the rider operates the input member 1751, the front master cylinder 1753 r is activated to generate a hydraulic pressure. The hydraulic pressure generated is then transmitted to the hydraulic pressure controller 1755 by way of the front brake hose 1704. The electronic controller 1755 a of the hydraulic pressure controller 1755 controls the hydraulic pressure unit 1755 b so as to generate a hydraulic pressure which corresponds to the hydraulic pressure transmitted thereto and a rotating speed of each wheel. The hydraulic pressure generated in the hydraulic pressure unit 1755 b is transmitted to the right caliper 1722 by way of the right front brake hose 1724. This activates the right front brake 1072. The hydraulic pressure generated in the hydraulic pressure unit 1755 b is transmitted to the left caliper 1712 by way of the left brake hose 1714. This activates the left front brake 1071. The first preferred embodiment shown in FIG. 9 includes an actuator for the right front brake 1072, an actuator for the left front brake 1071, and an actuator for the central rear brake 1073. The hydraulic pressures of the right front brake 1072, the left front brake 1071 and the central rear brake 1073 are able to be controlled independently of one another. The second brake activator 1754 includes a rear master cylinder 17531. When the rider operates the second input member 1752, the rear master cylinder 17531 is activated to generate a hydraulic pressure. The hydraulic pressure generated is transmitted to the hydraulic pressure controller 1755 by way of the brake hose. The electronic controller 1755 a of the hydraulic pressure controller 1755 controls the hydraulic pressure unit 1755 b so as to generate a hydraulic pressure which corresponds to the hydraulic pressure transmitted thereto and a rotating speed of each wheel. The hydraulic pressure generated in the hydraulic pressure unit 1755 b is transmitted to the central rear caliper 1732 by way of the rear brake hose 1734. This activates the central rear brake 1073. The hydraulic pressure generated in the hydraulic pressure unit 1755 b is transmitted to the right caliper 1722 by way of the right front brake hose 1724. This activates the right front brake 1072. The hydraulic pressure generated in the hydraulic pressure unit 1755 b is transmitted to the left caliper 1712 by way of the left brake hose 1714. This activates the left front brake 1071. The first preferred embodiment shown in FIG. 9 includes an actuator for the right front brake 1072, an actuator for the left front brake 1071, and an actuator for the central rear brake 1073. The hydraulic pressures of the right front brake 1072, the left front brake 1071 and the central rear brake 1073 are able to be controlled independently of one another. Timings at which braking forces are generated on the right front wheel 1032, the left front wheel 1031 and the central rear wheel 1004 as a result of operation of the right front brake 1072, the left front brake 1071 and the central rear brake 1073 and magnitudes of the braking forces generated are set as required. The timings may be the same as or different from one another. The magnitudes may increase in the same way or differently.

The hydraulic pressure controller 1755 shown in FIG. 9 may be activated in the following manner. When a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the hydraulic pressure controller 1755 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the left detector 1812. When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the hydraulic pressure controller 1755 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the right detector 1822. When a slipping condition of the central rear wheel 1004 is detected based on a signal detected by the rear detector 1832, the hydraulic pressure controller 1755 reduces a braking force on the central rear wheel 1004 to a lower level than a level of a braking force which is obtained as a result of operation of the second input member 1752 by controlling the operating condition of the central rear brake 1073 on the central rear wheel 1004 based on the signal detected by the rear detector 1832. The hydraulic pressure controller 1755 is able to control individually the operations of the left front brake 1071, the right front brake 1072 and the central rear brake 1073. The hydraulic pressure controller 1755 is able to control individually the braking forces on the left front wheel 1031, the right front wheel 1032 and the central rear wheel 1004.

FIG. 10 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 8. FIG. 10 shows the brake system 1702 shown in FIG. 8 in detail. FIG. 10 shows a modified example of the brake system 1702 shown in FIG. 9. A second preferred embodiment shown in FIG. 10 is basically the same as the preferred embodiment shown in FIG. 9. The second preferred embodiment shown in FIG. 10 includes an actuator for the right front brake 1072 and the left front brake 1071, and an actuator for the central rear brake 1073. A hydraulic pressure by the actuator for the right front brake 1072 and the left front brake 1071 is divided to be transmitted to the right front brake 1072 and the left front brake 1071 by way of the right front brake hose 1724 and the left brake hose 1714, respectively. The hydraulic pressures of the left front brake 1071 and the central rear brake 1073 are able to be controlled independently of each other. In the present preferred embodiment, however, the hydraulic pressures of the right front brake 1072 and the left front brake 1071 are set to be the same.

FIG. 11 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 8. FIG. 11 shows the brake system 1702 shown in FIG. 8 in detail. FIG. 11 shows a modified example of the brake systems 1702 shown in FIGS. 9 and 10. The third preferred embodiment shown in FIG. 11 is basically the same as the preferred embodiment shown in FIG. 10. The third preferred embodiment shown in FIG. 11 includes an actuator for the right front brake 1072 and the left front brake 1071, and an actuator for the central rear brake 1073. A hydraulic pressure by the actuator for the right front brake 1072 and the left front brake 1071 is divided at a brake hose to be transmitted to the right front brake 1072 and the left front brake 1071 by way of the right front brake hose 1724 and the left brake hose 1714, respectively. The hydraulic pressures of the left front brake 1071 and the central rear brake 1073 are able to be controlled independently of each other. In the present preferred embodiment, however, the hydraulic pressures of the right front brake 1072 and the left front brake 1071 are set to be the same. Further, in the third preferred embodiment, the second brake activator 1754 includes a mechanical mechanism that changes the timing at which the hydraulic pressures are applied to activate the brakes. In the third preferred embodiment, the second brake activator 1754 includes the rear master cylinder 17531, an operating force generating mechanism 1753 a, an operating force transmitting mechanism 1753 b, a timing changing mechanism 1753 c, and the front master cylinder 1753 r. When the second input member 1752 is operated by the rider, the operating force generating mechanism 1753 a is activated in association with the operation of the second input member 1752 by the rider. The operation of the operating force generating mechanism 1753 a is transmitted to the timing changing mechanism 1753 c via the operating force transmitting mechanism 1753 b. The timing changing mechanism 1753 c activates the front master cylinder 1753 r with a certain time lag relative to the operation which is transmitted thereto from the operating force transmitting mechanism 1753 b. The operation of the front master cylinder 1753 r to be performed thereafter will be the same as that of the preferred embodiment described above. The time lag is generated not by the hydraulic pressure controller 1755 but by the operating force generating mechanism 1753 a, the operating force transmitting mechanism 1753 b and the timing changing mechanism 1753 c.

FIG. 12 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 8. FIG. 12 shows the brake system 1702 shown in FIG. 8 in detail. FIG. 12 shows a modified example of the brake systems 1702 shown in FIGS. 9, 10, and 11. The fourth preferred embodiment shown in FIG. 12 is basically the same as the preferred embodiment shown in FIG. 11. The fourth preferred embodiment shown in FIG. 12 includes an actuator for the right front brake 1072 and the left front brake 1071. A hydraulic pressure by the actuator for the right front brake 1072 and the left front brake 1071 is divided at a halfway portion of a brake hose to be transmitted to the right front brake 1072 and the left front brake 1071 by way of the right front brake hose 1724 and the left brake hose 1714, respectively. The hydraulic pressures of the right front brake 1072 and the left front brake 1071 are able to be controlled independently of each other. In the present preferred embodiment, however, the hydraulic pressures of the right front brake 1072 and the left front brake 1071 are set to be the same. Further, in the fourth preferred embodiment, the second brake activator 1754 includes a mechanical mechanism that changes the timing at which the hydraulic pressures are applied to activate the brakes. In the fourth preferred embodiment, the second brake activator 1754 includes the rear master cylinder 17531, an operating force generating mechanism 1753 a, an operating force transmitting mechanism 1753 b, a timing changing mechanism 1753 c, and the front master cylinder 1753 r. When the second input member 1752 is operated by the rider, the operating force generating mechanism 1753 a is activated in association with the operation of the second input member 1752 by the rider. The operation of the operating force generating mechanism 1753 a is transmitted to the timing changing mechanism 1753 c via the operating force transmitting mechanism 1753 b. The timing changing mechanism 1753 c activates the front master cylinder 1753 r with a certain time lag relative to the operation which is transmitted thereto from the operating force transmitting mechanism 1753 b. The operation of the front master cylinder 1753 r to be performed thereafter will be the same as that of the preferred embodiment described above. The time lag is generated not by the hydraulic pressure controller 1755 but by the operating force generating mechanism 1753 a, the operating force transmitting mechanism 1753 b and the timing changing mechanism 1753 c. When the rider operates the second input member 1752, the rear master cylinder 17531 is activated to generate a hydraulic pressure. The hydraulic pressure generated is transmitted to the central rear caliper 1732 by way of the rear brake hose 1734. Upon receipt of the hydraulic pressure, the central rear caliper 1732 holds the central rear brake disc 1731 with the brake pads. This activates the central rear brake 1073 to generate a differential force in the central rear wheel 1004.

FIG. 13 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 8. FIG. 13 shows the brake system 1702 shown in FIG. 8 in detail. FIG. 13 shows a modified example of the brake systems 1702 shown in FIGS. 9, 10, 11, and 12. The fifth preferred embodiment shown in FIG. 13 is basically the same as the preferred embodiment shown in FIG. 11. The fifth preferred embodiment shown in FIG. 13 includes an actuator for the central rear brake 1073. The hydraulic pressure generated by the actuator for the central rear brake 1073 is transmitted to the central rear brake 1073 by way of the rear brake hose 1734. The hydraulic pressure at the central rear brake 1073 is able to be controlled. Further, in the third preferred embodiment, the second brake activator 1754 includes a mechanical mechanism that changes the timing at which the hydraulic pressures are applied to activate the brakes. In the third preferred embodiment, the second brake activator 1754 includes the rear master cylinder 17531, an operating force generating mechanism 1753 a, an operating force transmitting mechanism 1753 b, a timing changing mechanism 1753 c, and the front master cylinder 1753 r. When the second input member 1752 is operated by the rider, the operating force generating mechanism 1753 a is activated in association with the operation of the second input member 1752 by the rider. The operation of the operating force generating mechanism 1753 a is transmitted to the timing changing mechanism 1753 c via the operating force transmitting mechanism 1753 b. The timing changing mechanism 1753 c activates the front master cylinder 1753 r with a certain time lag relative to the operation which is transmitted thereto from the operating force transmitting mechanism 1753 b. The operation of the front master cylinder 1753 r to be performed thereafter will be the same as that of the preferred embodiment described above. The time lag is generated not by the hydraulic pressure controller 1755 but by the operating force generating mechanism 1753 a, the operating force transmitting mechanism 1753 b and the timing changing mechanism 1753 c.

FIG. 14 shows an example of a preferred embodiment of the brake system 1702 shown in FIGS. 11, 12, and 13. FIG. 14 shows the brake systems 1702 shown in FIGS. 11, 12, and 13 in detail. FIG. 14 shows a modified example of the brake systems 1702 shown in FIGS. 11, 12, 13. The sixth preferred embodiment shown in FIG. 14 shows an example of the operating force generating mechanism 1753 a, the operating force transmitting mechanism 1753 b and the timing changing mechanism 1753 c. The second input member 1752 is preferably a lever which is able to swing about a rotating shaft 63 a. When the second input member 1752 is operated, a first operating portion 63 b provided on the second input member 1752 pushes the rear master cylinder 17531. This activates the rear master cylinder 17531 to generate a hydraulic pressure. The hydraulic pressure generated is transmitted to the rear brake hose 1734. When the input member 1751 is operated, a second operating portion 63 c provided on the input member 1751 activates a third operating portion 70 to activate the operating force transmitting mechanism 1753 b, which preferably includes a wire. The operation of the operating force transmitting mechanism 1753 b is transmitted to a spring 57. As this occurs, a larger force than an elastic restoring force of the spring is transmitted to the spring 57 so that the spring 57 is deformed, thus activating a connecting member 54. When the connecting member 54 is activated, a fourth operating portion 53 c and a fifth operating portion 53 b are activated to push the front master cylinder 1753 r. This activates the front master cylinder 1753 r to generate a hydraulic pressure. The hydraulic pressure generated is transmitted to the front brake hose 1704. According to this configuration, although the second input member 1752 is operated, the front master cylinder 1753 r is not activated immediately. Thereafter, by operating further the second input member 1752, the front master cylinder 1753 r is activated with a certain time lag. By changing its size or the like, the mechanical mechanism is able to change not only the timing at which the hydraulic pressure is generated but also the magnitude of a hydraulic pressure to be generated.

The input member 1751 is preferably a lever member which is able to swing about a rotating shaft 53 a. When the input member 1751 is operated, the sixth operating portion 53 d and the fifth operating portion 53 b are activated and push the front master cylinder 1753 f. This activates the front master cylinder 1753 r to generate a hydraulic pressure. The hydraulic pressure generated is transmitted to the front brake hose 1704. The operating force generating mechanism 1753 a includes the first operating portion 63 b, the second operating portion 63 c and the third operating portion 70. The operating force transmitting mechanism 1753 b preferably includes the wire. The timing changing mechanism 1753 c includes the spring 57, the connecting member 54, the fourth operating portion 53 c, the fifth operating portion 53 b and the sixth operating portion 53 d. In the second brake activator 1754, the operating force generating mechanism 1753 a, the operating force transmitting mechanism 1753 b, the timing changing mechanism 1753 c, the rear master cylinder 17531, the front master cylinder 1753 r, the front brake hose 1704 and the rear brake hose 1734. The brake activator 1756 includes the sixth operating portion 53 d, the fifth operating portion 53 b, the front master cylinder 1753 r and the front brake hose 1704.

As shown in FIG. 1, the hydraulic pressure controller 1755 is disposed directly ahead of the link mechanism 1005 in the front-and-rear direction of the vehicle 1001. The hydraulic pressure controller 1755 is supported on the body frame 1021 via a bracket. As shown in FIG. 1, the hydraulic pressure controller 1755 may be disposed in the body frame 1021 below a foot resting board where the rider places his or her feet. Additionally, the hydraulic pressure controller 1755 may be disposed below the seat 1024 where the rider sits. The hydraulic pressure controller 1755 may be disposed in the body frame 1021 inwards of the body cover 1022. The handlebar 1023 of the steering mechanism 1007 is preferably a bar which extends in the left-and-right direction of the body frame 1021. The handlebar 1023 includes at a right end portion thereof a right grip 1007 r which the rider grips. The handlebar 1023 includes at a left end portion thereof a left grip 10071 which the rider grips. The input member 1752 and the second input member 1752 are able to be operated by the rider while the rider grips the right grip 1007 r and the left grip 10071.

FIG. 15 shows an example of a preferred embodiment of the brake system 1702 shown in FIG. 9. FIG. 15 shows the brake system 1702 shown in FIG. 9 in detail. FIG. 15 shows an example of the hydraulic pressure unit 1755 b. This hydraulic pressure unit 1755 b includes a motor 1755 b 1 which generates a hydraulic pressure. The hydraulic pressure unit 1755 b includes a buffer chamber 1755 b 2 which stores fluid. The hydraulic pressure unit 1755 b includes a solenoid valve 1755 b 3. The hydraulic pressure unit 1755 b includes a throttle 1755 b 4. The motor 1755 b 1 is controlled by an electronic controller 1755 a. The solenoid valve 1755 b 3 is controlled by the electronic controller 1755 a. The electronic controller 1755 a controls the motor 1755 b 1 and the solenoid valve 1755 b 3 to activate the left front brake 1071, the right front brake 1072 and the central rear brake 1073.

The second brake activator 1754 activates the central rear brake 1073 when an operation quantity of the second input member 1752 from an initial position is a first operation quantity at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle. Thereafter, the second brake activator 1754 activates the front brake which is provided on the front wheel which defines the inner wheel having a smaller turning radius when the operation quantity of the second input member 1752 from the initial position is a second operation quantity which is larger than the first operation quantity. Thereafter, the second brake activator 1754 makes a sum of both braking forces in the front wheel which defines the outer wheel and the front wheels which defines the inner wheel larger than a braking force on the central rear wheel 1004 when the operation quantity of the second input member 1752 from the initial positions is a third quantity which is larger than the second operation quantity. Here, the second input member 1752 is preferably a lever. The second input member 1752 is a lever which swings between the initial position to a maximum operated position. The initial position is a position where the second input member 1752 is not operated by the rider. The maximum operated position is a position where the second input member 1752 is operated to swing most or farthest away from the initial position. The first operation quantity is smaller than the second operation quantity. The second operation quantity is smaller than the third operation quantity. In expressing this relationship based on the position of the lever, the lever is positioned closer to the initial position when the operation quantity is the first operation quantity than when the operation quantity is the second operation quantity. The lever is positioned closer to the initial position when the operation quantity is the second operation quantity than when the operation quantity is the third operation quantity. The lever is positioned farther away from the maximum operated position when the operation quantity is the first operation quantity than when the operation quantity is the second operation quantity. The lever is positioned farther away from the maximum operated position when the operation quantity is the second operation quantity than when the operation quantity is the third operation quantity. The input member 1751 and the second input member 1752 are not limited to the lever and hence may be replaced by a pedal or a button.

The second brake activator 1754 operates in the following manner at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle. The second brake activator 1754 activates first the central rear brake 1073 in the right front brake 1072, the left front brake 1071 and the central rear brake 1073 as a result of operation of the second input member 1752. The second brake activator 1754 activates last the front brake which is provided on the front wheel which defines the inner wheel having the smaller turning radius in the right front brake 1072, the left front brake 1071 and the central rear brake 1073 as a result of operation of the second input member 1752. The second brake activator 1754 makes a sum of both the braking forces in the front wheel which defines the outer wheel and the front wheel which defines the inner wheel larger than the braking force on the central rear wheel as a result of operation of the second input member 1751. In the present preferred embodiment, a control has been described which is executed when the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle has been described. The present invention does not exclude the operation of the second brake activator 1754 in the above manner in other cases than the case where the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle, for example, in a case where the vehicle is running with the body frame 1021 being in the upright state. The present invention includes all preferred embodiments in which the second brake activator 1754 operates in the above manner at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle.

In the present preferred embodiment, the brake system 1702 includes the right front brake 1072, the left front brake 1071, the single input member 1751 and the brake activator 1756 which activates the right front brake 1072 and the left front brake 1071 as a result of operation of the input member 1751. Because of this, the brake system 1702 is able to be used for the vehicle 1001 which includes the body frame 1021 which leans, the right front wheel 1032, the left front wheel 1031, and the central rear wheel 1004.

The vehicle 1001 including the body frame 1021 which leans, the right front wheel 1032, the left front wheel 1031, and the central rear wheel 1004 exhibits the following characteristics while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle.

When the vehicle is turning with the body frame 1021 leaning to the right of the vehicle, the right front wheel 1032 defines the inner wheel having the smaller turning radius, and the left front wheel 1031 defines the outer wheel having the larger turning radius. When the vehicle is turning with the body frame 1021 leaning to the left of the vehicle, the left front wheel 1031 defines the inner wheel having the smaller turning radius, and the right front wheel 1032 defines the outer wheel having the larger turning radius. Since the vehicle is turning while causing the body frame 1021 to lean in the left-and-right of the vehicle by the link mechanism 1005 at least a portion of which is supported on the body frame 1021 so as to turn about the turning axis which extends forwards in the front-and-rear direction of the body frame 1021 and upwards in the up-to-right direction of the body frame 1021, the vehicle has a tendency that a load applied to the front wheel which defines the inner wheel becomes larger basically than a load which is applied to the front wheel which defines the outer wheel of the vehicle which is turning. Moreover, the vehicle including the single central rear wheel 1004 has a tendency that a load applied to the front wheels becomes larger relatively than a load applied to the rear wheel, compared with a vehicle including a left rear wheel and a right rear wheel. Because of this, the vehicle has a tendency that the load applied to the front wheel which defines the inner wheel basically becomes larger than the load applied to the front wheel which defines the outer wheel of the vehicle which is turning. In addition, the front wheel which defines the inner wheel and the front wheel which defines the outer wheel of the vehicle which is turning pass over different road surfaces. Because of this, there is a possibility that the two front wheels pass over road surfaces having different friction coefficients.

The inventor of the present invention has studied brake systems while taking into consideration the characteristics of the vehicle having the body frame which leans, the two front wheels, and the single rear wheel. Additionally, the inventor has studied the braking forces on the right front wheel 1032 and the left front wheel 1031 at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle and the right front brake 1072 and the left front brake 1071 are in operation. As a result of the studies, it has been discovered that when a slipping condition of the front wheel which defines the inner wheel is not detected but a slipping condition of the front wheel which defines the outer wheel is detected based on signals detected by the right detector 1822 and the left detector 1812, in case the braking force on the front wheel which defines the outer wheel is reduced to a lower level than a level of a braking force which is obtained by operating the input member 1751 by controlling the operating condition of the front brake of the front wheel which defines the outer wheel which is in the slipping condition, a difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large. When the difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large and the braking force on the front wheel which defines the inner wheel becomes larger than the braking force on the front wheel which defines the outer wheel, a force is applied to the body frame which acts in a direction in which the leaning angle of the body frame from the vertical direction is reduced. In addition, when the difference between the braking force on the front wheel which defines the inner wheel and the braking force on the front wheel which defines the outer wheel becomes large and the braking force on the front wheel which defines the inner wheel becomes smaller than the braking force on the front wheel which defines the outer wheel, a force is applied to the body frame which acts in a direction in which the leaning angle of the body frame from the vertical direction is increased.

The inventor of the preferred embodiments of the present invention conceived a brake system which takes this condition into consideration.

The brake activator 1756 operates in the following manner at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle and the right front brake 1072 and the left front brake 1071 are both in operation as a result of operation of the input member 1751. When a slipping condition of the right front wheel 1032 is detected based on a signal detected by the right detector 1822, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force on the right front wheel 1032 which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the right detector 1822. In addition, the brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force on the left front wheel 1031 which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the right detector 1822. The brake activator 1756 operates in the following manner at least while the vehicle is turning with the body frame 1021 leaning in the left-and-right direction of the vehicle and the right front brake 1072 and the left front brake 1071 are both in operation as a result of operation of the input member 1751. When a slipping condition of the left front wheel 1031 is detected based on a signal detected by the left detector 1812, the brake activator 1756 reduces a braking force on the left front wheel 1031 to a lower level than a level of a braking force on the left front wheel 1031 which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the left front brake 1071 on the left front wheel 1031 based on the signal detected by the left detector 1812. In addition, the brake activator 1756 reduces a braking force on the right front wheel 1032 to a lower level than a level of a braking force on the right front wheel 1032 which is obtained as a result of operation of the input member 1751 by controlling the operating condition of the right front brake 1072 on the right front wheel 1032 based on the signal detected by the left detector 1812. The brake activator 1756 operates in the following manner while the vehicle is turning with the body frame 1021 leaning and the right front brake 1072 and the left front brake 1071 are both in operation. The brake activator 1756 reduces both braking forces on the left front wheel 1031 and the right front wheel 1032 to a lower level than a level of a braking force which is obtained as a result of operation of the input member 1751 by controlling both the operating conditions of the right front brake 1072 and the left front brake 1071 based on a detection signal of one of the right detector 1822 and the left detector 1812. This restricts the difference in braking force between the right front wheel 1032 and the left front wheel 1031. This also includes the following effects. It is possible to restrict an expansion in difference in braking force between the right front wheel 1032 and the left front wheel 1031. It is possible to restrict an increase in difference in braking force between the right front wheel 1032 and the left front wheel 1031. It is possible to restrict an increase in difference in braking force between the right front wheel 1032 and the left front wheel 1031 to a larger value than a value which is obtained experimentally in advance. It is possible to restrict a period of time during which a difference in braking force between the right front wheel 1032 and the left front wheel 1031 is present. It is possible to shorten the period of time during which the difference in braking force between the right front wheel 1032 and the left front wheel 1031 is present. It is possible to reduce the difference in braking force between the right front wheel 1032 and the left front wheel 1031 in a short period of time. It is possible to provide a brake system for a vehicle including the body frame which leans, the two front wheels, and the single rear wheel and which differs in operation from the three brake systems which have conventionally been used. It is possible to restrict the difference in braking force between the right front wheel 1032 and the left front wheel 1031.

The up-and-down direction of the vehicle coincides with a vertical direction to the ground. The left-and-right direction of the vehicle coincides with a direction parallel to the ground. The vehicle described in the preferred embodiments is a vehicle which leans. With the vehicle leaning, the up-and-down direction of the vehicle coincides with the vertical direction to the ground. With the vehicle leaning, however, the body frame leans with respect to the ground. In other words, with the vehicle being in the upright state, the up-and-down direction of the body frame coincides with the up-and-down direction of the vehicle. With the vehicle leaning, however, the up-and-down direction of the body frame leans with respect to the up-and-down direction of the vehicle. With the vehicle being in the upright state, the left-and-right direction of the body frame coincides with the left-and-right direction of the vehicle. With the vehicle leaning, however, the left-and-right direction of the body frame leans with respect to the left-and-right direction of the vehicle. In the preferred embodiments, the description made is based on the up-and-down direction, left-and-right direction and front-and-rear direction of the vehicle.

Vehicles according to preferred embodiments of the present invention preferably include the body frame which leans and the two front wheels. The number of rear wheels is not limited to one and hence may be two. The vehicles may include the body cover which covers the body frame. The vehicles may not include the body cover which covers the body frame. The power source of the vehicle is not limited to the engine and hence, an electric motor may be used as the power source.

In the preferred embodiments described above, the lateral center of the central rear wheel preferably coincides with the lateral center between the right front wheel and the left front wheel. In the present invention, however, the lateral center of the central rear wheel may not coincide with the lateral center between the right front wheel and the left front wheel. In preferred embodiments of the present invention, when the vehicles are viewed from above with the body frame being in the upright state, it is preferable that the central rear wheel is present on a center line between the right front wheel and the left front wheel in relation to the left-and-right direction.

In the preferred embodiments described above, the input member is preferably a lever which the rider operates with his or her hand. However, the input member may be a pedal which the rider depresses with his or her foot. Additionally, the input member may be a push button or a rotary grip which is able to be operated by the rider. The input member is able to be operated between the initial state where the rider does not touch the input member with his or her hand or foot to the maximum operated state where the rider operates it most with his or her hand or foot. The input member is able to be operated between the initial state and the maximum operated state by the rider. The operation amount of the input member may include the position where the input member is in the initial state. As this occurs, the operation amount may be detected by providing a sensor which detects the position of the input member. The operation amount of the input member may be a variation in pressure from the initial state of the input member. As this occurs, the operation amount may be detected by providing a sensor which detects a hydraulic pressure generated by the master cylinder. In addition, the operation amount may be detected by providing a sensor which detects a pressure which is applied directly to the input member. The operation amount of the input member is a physical amount which changes according to the operation of the input member by the rider. The operation amount does not necessarily have to be detected by a sensor, and hence, a mechanism may be used which operates in mechanical association with the operation amount.

In the preferred embodiments described above, a disc brake which uses hydraulic pressure is preferably used for the brakes. However, the type of brake is not limited thereto, and hence, various types of brakes may be used which includes a drum brake, an electromagnetic brake, a wet multi-plate brake and the like.

In the preferred embodiments described above, a type of brake activator which controls hydraulic pressure electronically is preferably used for the brake activator. However, the brake activator is not limited to the type in which hydraulic pressures are controlled electronically, and hence, hydraulic pressures may be controlled with a mechanical mechanism. In addition, brake wires may be used in place of the brake hoses, so that the control is executed with the mechanical mechanism without using hydraulic pressures. As this occurs, the usage of an electric controller is not required.

In a preferred embodiment of the present invention, it is possible to use the type of brake activator which operates based on electronic control or mechanical mechanism and the brake system using the brake activator. As this occurs, in the brake activator which operates based on electronic control, although it is designed that the controls are carried out at the same time, in reality, there may be a situation where a slight time delay or lag occurs. In addition, in the brake activator which operates based on the mechanical mechanism, although it is designed that the controls are executed at the same time, there may be a situation where a slight time lag is generated due to an error of a mechanical part or a difference in length of the transmission lines of operating force. In a preferred embodiment, the slight time lag is ignored so that the controls are carried out at the same time. When referred to herein, “at the same time” has a broader meaning that that defined in dictionaries. Similarly, in the event that controls are carried out with a time lag which are able to provide the same working effect as that obtained when the controls are carried out at the same time, it is understood that the controls are carried out at the same time.

In a preferred embodiment of the present invention, the link mechanism may include further a cross member in addition to the upper cross member and the lower cross member. The upper cross member and the lower cross member are so called only from their relative positional relationship in the up-and-down direction. The upper cross member does not necessarily imply an uppermost cross member in the link mechanism. The upper cross member refers to a cross member which lies above a cross member which lies therebelow. The lower cross member does not necessarily imply a lowermost cross member in the link mechanism. The lower cross member refers to a cross member which lies below a cross member which lies above. Additionally, the cross member may include two portions of a right cross member and a left cross member. In this way, the upper cross member and the lower cross member may each include a plurality of portions as long as they still exhibit the link function. Further, another cross member may be provided between the upper cross member and the lower cross member. The link mechanism preferably includes the upper cross member and the lower cross member.

When referred to in this description, “parallel” includes two straight lines which do not intersect each other as members while they incline within the range of ±40 degrees. When referred to in relation to the “direction,” and the “member” in the preferred embodiments of the present invention, the term “along” also includes a case where the direction and the member are inclined within the range of ±40 degrees. When used together with a “direction” in the preferred embodiments of the present invention, “extend” also includes a case where what extends is inclined within the range of ±40° relative to the direction.

The terms and expressions which are used herein are used to describe the preferred embodiments of the present invention and hence should not be construed as limiting the scope of the present invention. It should be understood that any equivalents to the characteristic matters which are shown and described herein should not be excluded and that various modifications within the scope of claims to be made later are permitted.

The present invention can be embodied in many different forms. This disclosure should be understood to provide preferred embodiments of the present invention. Based on the understanding that the preferred embodiments which are described and/or illustrated herein are not intended to limit the present invention thereto, several preferred embodiments are described and illustrated herein.

Several illustrated preferred embodiments of the present invention are described herein. The present invention is not limited to the various preferred embodiments described herein. The present invention also includes every preferred embodiment which includes equivalent elements, modifications, deletions, combinations (for example, a combination of characteristics of various preferred embodiments), improvements and/or alternations which those skilled in the art to which the present invention pertains can recognize based on the disclosure herein. The limitative matters of claims should be construed broadly based on terms used in the claims and hence should not be limited by the preferred embodiments described in this description or the prosecution of the present invention. Those preferred embodiments should be construed as non-exclusive. For example, in this disclosure, the terms “preferably” and “may” should be construed as being non-exclusive and those terms mean, respectively, “preferable but not limited thereto” and “will be acceptable but not limited thereto.”

This application claims priority to Japanese Patent Application No. 2013-227454 filed on Oct. 31, 2013, the entire contents of which are incorporated herein by reference.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

1-11. (canceled) 12: A brake system for a vehicle, the brake system comprising: a right front brake on a right front wheel of the vehicle to generate a braking force on the right front wheel; a left front brake on a left front wheel of the vehicle to generate a braking force on the left front wheel; an input that is operated to turn by a rider; a right front wheel slip detector that detects a slipping condition of the right front wheel; a left front wheel slip detector that detects a slipping condition of the left front wheel; and a brake activator that: reduces the braking force on the right front wheel and the braking force on the left front wheel to a lower level than a level of a braking force which is obtained by an operation of the input by controlling both an operating condition of the right front brake on the right front wheel and an operating condition of the left front brake on the left front wheel based on a signal detected by the right front wheel slip detector at least while the vehicle is turning with the body frame leaning in a left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation as a result of the operation of the input when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector; and reduces the braking force on the left front wheel and the braking force on the right front wheel to a lower level than a level of a braking force which is obtained by an operation of the input by controlling both an operating condition of the left front brake on the left front wheel and an operating condition of the right front brake on the right front wheel based on a signal detected by the left front wheel slip detector when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector. 13: The brake system according to claim 12, wherein the brake activator: reduces the braking force on the left front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel according to a physical quantity in relation to the braking force on the right front wheel based on the signal detected by the right front wheel slip detector; and reduces the braking force on the right front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel according to a physical quantity in relation to the braking force on the left front wheel based on the signal detected by the left front wheel slip detector. 14: The brake system according to claim 13, wherein the brake activator: reduces the braking force on the left front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel according to a physical quantity in relation to the operating condition of the right front brake based on the signal detected by the right front wheel slip detector; and reduces the braking force on the right front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel according to a physical quantity in relation to the operating condition of the left front brake based on the signal detected by the left front wheel slip detector. 15: The brake system according to claim 12, wherein the brake activator reduces: the braking force on the left front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel according to a control quantity which controls the operating condition of the right front brake based on the signal detected by the right front wheel slip detector; and reduces the braking force on the right front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel according to a control quantity which controls the operating condition of the left front brake based on the signal detected by the left front wheel slip detector. 16: The brake system according to claim 12, wherein when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector, the brake activator firstly reduces the braking force on the right front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel and thereafter reduces the braking force on the left front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector; and when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector, the brake activator firstly reduces the braking force on the left front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel and thereafter reduces the braking force on the right front wheel to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector. 17: The brake system according to claim 12, wherein when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector, the brake activator reduces the braking force on the right front wheel and the braking force on the left front wheel at the same time to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the right front brake on the right front wheel and controlling the operating condition of the left front brake on the left front wheel based on the signal detected by the right front wheel slip detector; and when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector, the brake activator reduces the braking force on the right front wheel and the braking force on the left front wheel at the same time to a lower level than a level of the braking force which is obtained as a result of the operation of the input by controlling the operating condition of the left front brake on the left front wheel and controlling the operating condition of the right front brake on the right front wheel based on the signal detected by the left front wheel slip detector. 18: A vehicle comprising: a body frame; a right front wheel and a left front wheel aligned in a left-and-right direction of the body frame when the vehicle is viewed from a front thereof with the body frame being in an upright state; a central rear wheel provided behind the right front wheel and the left front wheel in a front-and-rear direction of the body frame and disposed between the right front wheel and the left front wheel when the vehicle is viewed from the front thereof with the body frame being in the upright state; a right shock absorber that supports the right front wheel at a lower portion thereof and absorbs an upward displacement of the right front wheel in an up-and-down direction of the body frame; a left shock absorber that supports the left front wheel at a lower portion thereof and absorbs an upward displacement of the left front wheel in the up-and-down direction of the body frame; a linkage above the right front wheel and the left front wheel in the up-and-down direction of the body frame when the vehicle is viewed from the front thereof with the body frame being in the upright state and that supports an upper portion of the right shock absorber and an upper portion of the left shock absorber so as to turn, at least a portion of which is supported on the body frame so as to turn about a turning axis which extends forwards in the front-and-rear direction of the body frame and upwards in the up-and-down direction of the body frame; a brake system including: a right front brake on the right front wheel to generate a braking force on the right front wheel; a left front brake on the left front wheel to generate a braking force on the left front wheel; an input that is operated to turn by a rider; a right front wheel slip detector that detects a slipping condition of the right front wheel; a left front wheel slip detector that detects a slipping condition of the left front wheel; and a brake activator that: reduces the braking force on the right front wheel and the braking force on the left front wheel to a lower level than a level of a braking force which is obtained by an operation of the input by controlling both an operating condition of the right front brake on the right front wheel and an operating condition of the left front brake on the left front wheel based on a signal detected by the right front wheel slip detector at least while the vehicle is turning with the body frame leaning in a left-and-right direction of the vehicle and both the right front brake and the left front brake are in operation as a result of the operation of the input when the slipping condition of the right front wheel is detected based on the signal detected by the right front wheel slip detector; and reduces the braking force on the left front wheel and the braking force on the right front wheel to a lower level than a level of a braking force which is obtained by an operation of the input by controlling both an operating condition of the left front brake on the left front wheel and an operating condition of the right front brake on the right front wheel based on a signal detected by the left front wheel slip detector when the slipping condition of the left front wheel is detected based on the signal detected by the left front wheel slip detector. 19: The vehicle according to claim 18, wherein the right shock absorber includes a right telescopic arm that extends and contracts in an extending and contracting direction extending in the up-and-down direction of the body frame and allows the right front wheel to be displaced in the extending and contracting direction of the right telescopic arm; and the left shock absorber includes a left telescopic arm that extends and contracts in an extending and contracting direction extending in the up-and-down direction of the body frame and allows the left front wheel to be displaced in the extending and contracting direction of the left telescopic arm. 20: The vehicle according to claim 18, wherein the linkage is above the right front wheel and the left front wheel in the up-and-down direction of the body frame when the vehicle with the body frame being in the upright state is viewed from the front thereof; and the right front wheel and the left front wheel overlap the central rear wheel when the vehicle is viewed from the front thereof with the right shock absorber and the left shock absorber turned most relative to the linkage. 21: The vehicle according to claim 18, further comprising a second brake system including: a second input which differs from the input; and a second brake activator that activates the right front brake, the left front brake, and a central rear brake provided on the central rear wheel as a result of an operation of the second input at least while the vehicle is turning with the body frame leaning in the left-and-right direction of the vehicle. 22: The vehicle according to claim 21, wherein the second brake activator activates the right front brake and the left front brake by using at least a portion of the brake activator. 